Question

activity 1
multiply the decimal numbers together. choose the correct answer.

1. 0.8·0.9

(a) 0.72
(b) 0.072
(c) 7.2

1. 0.02·0.25

(a) 0.50
(b) 0.0050
(c) 0.050

1. 0.75·0.2

(a) 0.15
(b) 0.015
(c) 1.50

1. 0.5·4.8

(a) 0.024
(b) 0.24
(c) 2.40
activity 2
multiply using the traditional method. check your work using rounding

1. 0.75·0.8
2. 0.029·0.1
3. 0.54·0.7
4. 0.25·0.4
5. 0.1·0.08
6. 2.5·0.5

activity 3
circle the graphs that show indirect relationships.
graph a
graph b
graph c
graph d

Explanation:

Activity 1

1. Calculate $0.8\times0.9$

Multiply as if they were whole - numbers: $8\times9 = 72$. There are a total of $1 + 1=2$ decimal places in the factors. So, $0.8\times0.9 = 0.72$. The answer is (a).

2. Calculate $0.02\times0.25$

Multiply as whole - numbers: $2\times25 = 50$. There are $2+2 = 4$ decimal places in the factors. So, $0.02\times0.25=0.0050$. The answer is (b).

3. Calculate $0.75\times0.2$

Multiply as whole - numbers: $75\times2 = 150$. There are $2 + 1=3$ decimal places in the factors. So, $0.75\times0.2 = 0.15$. The answer is (a).

4. Calculate $0.5\times4.8$

Multiply as whole - numbers: $5\times48 = 240$. There are $1+1 = 2$ decimal places in the factors. So, $0.5\times4.8 = 2.40$. The answer is (c).

Activity 2

1. Calculate $0.75\times0.8$

Multiply as whole - numbers: $75\times8 = 600$. There are $2 + 1=3$ decimal places in the factors. So, $0.75\times0.8 = 0.600=0.6$.
Rounding: $0.75\approx0.8$ and $0.8$ remains $0.8$, $0.8\times0.8 = 0.64$, which is close to $0.6$.

2. Calculate $0.029\times0.1$

Multiply as whole - numbers: $29\times1 = 29$. There are $3+1 = 4$ decimal places in the factors. So, $0.029\times0.1=0.0029$.
Rounding: $0.029\approx0.03$ and $0.1$ remains $0.1$, $0.03\times0.1 = 0.003$, which is close to $0.0029$.

3. Calculate $0.54\times0.7$

Multiply as whole - numbers: $54\times7 = 378$. There are $2+1 = 3$ decimal places in the factors. So, $0.54\times0.7 = 0.378$.
Rounding: $0.54\approx0.5$ and $0.7$ remains $0.7$, $0.5\times0.7 = 0.35$, which is close to $0.378$.

4. Calculate $0.25\times0.4$

Multiply as whole - numbers: $25\times4 = 100$. There are $2+1 = 3$ decimal places in the factors. So, $0.25\times0.4 = 0.100 = 0.1$.
Rounding: $0.25\approx0.3$ and $0.4$ remains $0.4$, $0.3\times0.4 = 0.12$, which is close to $0.1$.

5. Calculate $0.1\times0.08$

Multiply as whole - numbers: $1\times8 = 8$. There are $1+2 = 3$ decimal places in the factors. So, $0.1\times0.08 = 0.008$.
Rounding: $0.1$ remains $0.1$ and $0.08\approx0.1$, $0.1\times0.1 = 0.01$, which is close to $0.008$.

6. Calculate $2.5\times0.5$

Multiply as whole - numbers: $25\times5 = 125$. There are $1+1 = 2$ decimal places in the factors. So, $2.5\times0.5 = 1.25$.
Rounding: $2.5$ remains $2.5$ and $0.5$ remains $0.5$, $2.5\times0.5 = 1.25$.

Activity 3

An indirect relationship (inverse relationship) in a graph shows that as one variable increases, the other variable decreases. Without seeing the actual plotted points on the graphs, we assume that if the graph has a negative - slope (a line going downwards from left to right), it represents an indirect relationship. Since no data points are given for the graphs A, B, C, and D, we cannot give a definite answer for this part.

Answer:

Activity 1

1. a. 0.72
2. b. 0.0050
3. a. 0.15
4. c. 2.40

Activity 2

1. 0.6
2. 0.0029
3. 0.378
4. 0.1
5. 0.008
6. 1.25

Activity 3

No definite answer due to lack of graph data.