forensic science chapter 2
name: ___________________________ period: _____
crime scene review worksheet
1. ______ a location other than where the crime took place, but is in some way related to the crime and where evidence is found a. chain of custody
2. ______ a material that can be related to a single source b. circumstantial evidence
3. ______ a written record of all people who have had possession of an item of evidence c. class evidence
4. ______ any place where evidence maybe located to help explain events d. collusion
5. ______ evidence that (if true) proves an alleged fact, such as an eyewitness account of a crime e. control sample
6. ______ indirect evidence; evidence used to imply a fact but not prove it directly f. crime scene
7. ______ material that comes from a proven or known source g. direct evidence
8. ______ material that connects an individual or thing to a group that share similar characteristics h. district attorney
9. ______ small but measurable amounts of physical or biological material found at a crime scene i. first responder
10. ______ the elected or appointed official who represents the government in the prosecution of a crime j. individual evidence
11. ______ the first police officer to arrive at a crime scene k. locard exchange principle
12. ______ the location where the crime took place l. primary crime scene
13. ______ there is always a cross transfer of evidence between a suspect and victim or locale m. secondary crime scene
14. ______ when witness or suspects create story of what happened at a crime n. trace evidence
fill-in and short answer questions
15. most wrongful convictions seem to be the result of ______________________________.
16. a pair of latex gloves was found at a crime scene. a box of the same brand of latex gloves was found at a suspect’s home.
• are the gloves individual or class evidence?
• can the gloves be individualized to the box?
17. in a class of 25 students, 8 were wearing a pink shirt. in the same class, 17 students had on blue jeans. eyewitnesses all stated that the suspect was in the class, and wearing both a pink shirt and blue jeans. according to the laws of probability, what percent of the class could be the suspect? show your work.

Question

forensic science chapter 2
name: ___________________________ period: _____
crime scene review worksheet
1. ______ a location other than where the crime took place, but is in some way related to the crime and where evidence is found  a. chain of custody
2. ______ a material that can be related to a single source  b. circumstantial evidence
3. ______ a written record of all people who have had possession of an item of evidence  c. class evidence
4. ______ any place where evidence maybe located to help explain events  d. collusion
5. ______ evidence that (if true) proves an alleged fact, such as an eyewitness account of a crime  e. control sample
6. ______ indirect evidence; evidence used to imply a fact but not prove it directly  f. crime scene
7. ______ material that comes from a proven or known source  g. direct evidence
8. ______ material that connects an individual or thing to a group that share similar characteristics  h. district attorney
9. ______ small but measurable amounts of physical or biological material found at a crime scene  i. first responder
10. ______ the elected or appointed official who represents the government in the prosecution of a crime  j. individual evidence
11. ______ the first police officer to arrive at a crime scene  k. locard exchange principle
12. ______ the location where the crime took place  l. primary crime scene
13. ______ there is always a cross transfer of evidence between a suspect and victim or locale  m. secondary crime scene
14. ______ when witness or suspects create story of what happened at a crime  n. trace evidence
fill-in and short answer questions
15. most wrongful convictions seem to be the result of ______________________________.
16. a pair of latex gloves was found at a crime scene. a box of the same brand of latex gloves was found at a suspect’s home.
    • are the gloves individual or class evidence?
    • can the gloves be individualized to the box?
17. in a class of 25 students, 8 were wearing a pink shirt. in the same class, 17 students had on blue jeans. eyewitnesses all stated that the suspect was in the class, and wearing both a pink shirt and blue jeans. according to the laws of probability, what percent of the class could be the suspect? show your work.

Accepted Answer

### Question 1
# Brief Explanations:
The term for a location related to the crime but not the primary scene is "secondary crime scene". So match with M.
# Answer:
M. secondary crime scene

### Question 2
# Brief Explanations:
Evidence from a single source is "individual evidence". So match with J.
# Answer:
J. individual evidence

### Question 3
# Brief Explanations:
Record of evidence possession is "chain of custody". So match with A.
# Answer:
A. chain of custody

### Question 4
# Brief Explanations:
Place with evidence to explain events is "crime scene". So match with F.
# Answer:
F. crime scene

### Question 5
# Brief Explanations:
Evidence that proves a fact directly is "direct evidence". So match with G.
# Answer:
G. direct evidence

### Question 6
# Brief Explanations:
Indirect evidence is "circumstantial evidence". So match with B.
# Answer:
B. circumstantial evidence

### Question 7
# Brief Explanations:
Material from known source is "control sample". So match with E.
# Answer:
E. control sample

### Question 8
# Brief Explanations:
Evidence connecting to a group is "class evidence". So match with C.
# Answer:
C. class evidence

### Question 9
# Brief Explanations:
Small physical/biological material is "trace evidence". So match with N.
# Answer:
N. trace evidence

### Question 10
# Brief Explanations:
Official prosecuting crime is "district attorney". So match with H.
# Answer:
H. district attorney

### Question 11
# Brief Explanations:
First officer at scene is "first responder". So match with I.
# Answer:
I. first responder

### Question 12
# Brief Explanations:
Location of crime is "primary crime scene". So match with L.
# Answer:
L. primary crime scene

### Question 13
# Brief Explanations:
Cross - transfer of evidence is "Locard exchange principle". So match with K.
# Answer:
K. Locard exchange principle

### Question 14
# Brief Explanations:
Witnesses/suspects creating a story is "collusion". So match with D.
# Answer:
D. collusion

### Question 15
# Brief Explanations:
Most wrongful convictions result from eyewitness misidentification (or other factors like false confessions, but common is eyewitness misidentification).
# Answer:
eyewitness misidentification (or false confessions, etc. - common answer is eyewitness misidentification)

### Question 16
# Brief Explanations:
- For the first part: Class evidence is from a group, individual from a single source. The gloves (found at crime) and box (at suspect's home) of same brand - the gloves are class evidence as same - brand gloves are a group.
- For the second part: To individualize, need unique features. Same - brand gloves don't have unique features to link to that specific box, so no.
# Answer:
- Are the gloves individual or class evidence? Class evidence.
- Can the gloves be individualized to the box? No.

### Question 17
# Explanation:
## Step1: Find the number of students in the intersection
Let $ P $ be the set of students in pink shirts and $ B $ be the set in blue jeans. We use the principle of inclusion - exclusion. $ n(P\cap B)$ is what we need (students in both). But we assume independence (simplified for this problem). The number of students in pink is 8, in blue jeans is 17, total students $ N = 25$. The probability of a student being in both is $ \frac{n(P\cap B)}{N}$. But we can also calculate the number of students who can be in both. The maximum number of students in both is the minimum of 8 and 17, but we use the formula for the number of students in both when we consider the overlap. However, a simpler way: The number of students wearing pink is 8, so the proportion of pink - shirted is $ \frac{8}{25}$, and blue - jeaned is $ \frac{17}{25}$. The number of students in both is $ n(P\cap B)=n(P)+n(B)-n(P\cup B)$. But since $ n(P\cup B)\leq25$, $ n(P\cap B)\geq8 + 17-25=0$. But for the number of students who can be in both (wearing both), we assume that the number of students in both is the number of students in pink (since 8 is less than 17). Wait, actually, to find the number of students who are in both, we can think that the number of students wearing both is at most 8 (since only 8 are in pink). But the formula for the percentage is $ \frac{\text{Number of students in both}}{\text{Total students}}\times100$. But we can also calculate the probability of a student being in both as $ \frac{8}{25}\times\frac{17}{25}$ (if independent), but that's not correct. Wait, the correct way: The number of students who can be wearing both is the number of students in the intersection. The minimum of 8 and 17 is 8, but actually, we use the formula $ n(P\cap B)=n(P)+n(B)-n(P\cup B)$. Since $ n(P\cup B)\leq25$, $ n(P\cap B)\geq8 + 17 - 25=0$. But the number of students who are in both is the number of students who are in pink and in blue jeans. The number of students in pink is 8, so the number of students who can be in both is at most 8. But the percentage is $ \frac{\text{Number of students in both}}{25}\times100$. But we can also calculate the number of students who are in both as follows: Let $ x$ be the number of students in both. Then $ n(P\cup B)=8 + 17-x\leq25$, so $ x\geq0$. But the number of students who are in both is the number of students who are in pink and in blue jeans. The number of students in pink is 8, so the number of students who can be in both is 8 (since you can't have more than 8 in both if only 8 are in pink). Wait, no, the correct approach is: The number of students wearing a pink shirt is 8, and wearing blue jeans is 17. The number of students who can be wearing both is the number of students in the intersection. Using the formula for the intersection in a set, the maximum number of students in both is the size of the smaller set, which is 8. But the actual number of students in both is calculated as follows: Let's assume that all 8 students in pink shirts are also in blue jeans (the maximum possible overlap). Then the number of students in both is 8. The percentage is $ \frac{8}{25}\times100 = 32\%$. Wait, but another way: The probability that a student is in pink is $ \frac{8}{25}$, and in blue jeans is $ \frac{17}{25}$. If we assume independence (which may not be the case, but for the sake of the problem), the probability of being in both is $ \frac{8}{25}\times\frac{17}{25}=\frac{136}{625}=0.2176$, which is 21.76%. But this is a mistake. The correct way is to use the principle of inclusion - exclusion. The number of students in either pink or blue jeans is $ n(P\cup B)=n(P)+n(B)-n(P\cap B)$. We know that $ n(P\cup B)\leq25$, so $ n(P\cap B)=n(P)+n(B)-n(P\cup B)\geq8 + 17-25 = 0$. But the number of students who are in both is the number of students who are in pink and in blue jeans. The number of students in pink is 8, so the number of students who can be in both is 8 (since you can't have more than 8 students in both if only 8 are in pink). So the percentage is $ \frac{8}{25}\times100 = 32\%$. Wait, but let's think again. The problem says "According to the laws of probability, what percent of the class could be the suspect?". The suspect is in the class, wearing both. So we need to find the number of students who are in both pink and blue jeans. The number of students in pink is 8, in blue jeans is 17. The number of students who are in both is at least $ 8 + 17-25=0$ and at most 8. But the most probable number (using the principle of inclusion - exclusion for the minimum overlap is 0, but that doesn't make sense. Wait, no, the correct formula for the number of elements in the intersection is $ n(P\cap B)=n(P)+n(B)-n(P\cup B)$. Since $ n(P\cup B)\leq25$, $ n(P\cap B)\geq0$. But to find the number of students who could be the suspect (wearing both), we need to find the number of students in both. The number of students in both is $ n(P\cap B)$. We can also calculate the probability that a randomly selected student is in both as $ \frac{n(P\cap B)}{25}$. But we know that $ n(P\cap B)$ can be calculated as follows: The number of students in pink is 8, so the number of students not in pink is $ 25 - 8 = 17$. The number of students in blue jeans is 17, so the number of students in blue jeans and not in pink is at most 17 (but there are 17 students not in pink). So the number of students in blue jeans and in pink is $ 17-(17 - 8)=8$. Ah, that's the correct way. So $ n(P\cap B)=8$. Then the percentage is $ \frac{8}{25}\times100 = 32\%$.
## Step1: Calculate the number of students in both
Let $ P$ be the set of students in pink shirts and $ B$ be the set in blue jeans. We know $ n(P) = 8$, $ n(B)=17$, $ N = 25$. The number of students not in $ P$ is $ N - n(P)=25 - 8 = 17$. The number of students in $ B$ and not in $ P$ is at most 17 (since there are 17 students not in $ P$). So the number of students in $ B$ and in $ P$ is $ n(B)-(N - n(P))=17-(25 - 8)=8$.
## Step2: Calculate the percentage
The percentage is $ \frac{n(P\cap B)}{N}\times100=\frac{8}{25}\times100 = 32\%$.
# Answer:
32%

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