Question

Given that p varies jointly as q and r, and p = 7. when q = 2

and r= 1.5, find the following:

a. an equation relating p, q, and r
b. p when q = 4 and r= 6
c. p when p=1 and r=3
d. r when p= 5 and q = 8
​

Answer 1

P = k*q*r

Explanation:

P = kqr

7 = k*2*1.5

7 = 3k

k = 7/3

b. P = kqr

= 7/3*4*6

= (7*4*6)/3

= 168/3

= 56

P = 56

c. P = kqr

1 = 7/3*q*3

1 = (7*q*3)/3

1 = 21q/3

Cross product

1*3 = 21q

3 = 21q

q = 3/21

= 1/7

q = 1/7

d. P = kqr

5 = 7/3*8*r

5 = (7*8*r)/3

5*3 = 56r

15 = 56r

r = 15/56