5.1 Direct Variation (Sample Questions)


Example:
Given that p varies directly as square root of q and p = 12 when = 36, find
(a) The value of p when = 16
(b) The value of q when = 18

Solution:

p q , p = k q 12 = k 36
12 = k(6)
k = 2
p = 2 q

(a)
p = 2 q p = 2 16
p = 8

(b)   
p = 2 q 18 = 2 q 9 = q  
9² = q
q = 81