Question

c varies jointly with a and b.
when a = 2 and b = 3, c = 3.
what is the value of c when a = 4 and b = 5?
a. 10
b. 0.5
c. 14.4
d. 0.9

Explanation:

Step1: Define joint variation formula

$c = k \cdot a \cdot b$

Step2: Calculate constant k

$3 = k \cdot 2 \cdot 3 \implies k = \frac{3}{6} = 0.5$

Step3: Find c when a=4, b=5

$c = 0.5 \cdot 4 \cdot 5 = 10$

Answer:

A. 10