Question

1. for each of the following experiments, choose “scatter plot” or “bar graph” as the most appropriate way to display the data. justify your answer.

a. students heated oil on a hot plate at the #4 setting for different amounts of time. they wanted to answer the question “how long do you need to heat an oil bath to reach a given temperature?”

volume oil (ml)	hot plate setting	initial temp. of oil (°c)	time heated (min)	final temp. of oil (°c)
250	#4	21	5	30
250	#4	21	10	38
250	#4	21	15	47
250	#4	21	20	57

b. students measured the height of each student in class. they wanted to answer the question “what is the most common height among 10th grade students?”

height range	number of students
4’ 1” to 4’ 6”	3
4’ 7” to 5’ 0”	5
5’ 1” to 5’ 6”	9
5’ 7” to 6’ 0”	3
over 6’ 0”	1

c. the fish and wildlife agency measured the size of pacific salmon for 1 year and recorded the average weight for each species.

salmon species	average weight (lbs)
sockeye	8
silver	12
chum	15
humpback	5

d. the national oceanic and atmospheric administration measured the pressure of the atmosphere at various altitudes.

altitude (m)	atmos. pressure (atm)	altitude (m)	atmos. pressure (atm)
2750	0.750	30,901	0.010
5486	0.500	48,467	0.001
8376	0.333

Explanation:

Part (a)

Step1: Analyze Data Type

The data has two continuous variables: Time Heated (min) and Final Temp. of Oil (°C). We want to see the relationship between time and temperature.

Step2: Choose Graph Type

Scatter plots are used to show the relationship between two continuous variables. Bar graphs are for categorical vs. numerical or categorical vs. categorical. Here, both variables are continuous, so a scatter plot is appropriate. It will show how temperature changes with heating time.

Step1: Analyze Data Type

The data has a categorical variable (Height Range) and a numerical variable (Number of Students). We want to show the frequency of each height range.

Step2: Choose Graph Type

Bar graphs are suitable for comparing categorical groups (height ranges) with their frequencies (number of students). Scatter plots are for continuous vs. continuous, which isn't the case here. A bar graph will clearly show which height range has the most students.

Step1: Analyze Data Type

The data has a categorical variable (Salmon Species) and a numerical variable (Average Weight). We want to compare the average weights of different species.

Step2: Choose Graph Type

Bar graphs are used to compare categorical groups (species) with their numerical values (average weight). Scatter plots are not suitable here as one variable is categorical. A bar graph will easily show the weight differences between species.

Answer:

Scatter plot. Justification: The data has two continuous variables (time heated and final temperature), and a scatter plot shows the relationship between them.

Part (b)