Verified answer

Answer:

10.67

Step-by-step explanation:

To solve this problem, we can use the formula for joint variation, which is: p = k * q * r, where k is the constant of variation.

We can find the value of k by plugging in the given values for p, q, and r:

4 = k * 2 * 6

Simplifying this equation, we get:

k = 4 / (2 * 6) = 1/3

Now that we know the value of k, we can use the formula to find p when q = 4 and r = 8:

p = (1/3) * 4 * 8 = 10.67

Therefore, when q = 4 and r = 8, p is approximately equal to 10.67.