Joint variation - Jamb Mathematics Past Questions and Answers

Question 6:

• JAMB 1983

If x is jointly proportional to the cube of y and the fourth power of z. In what ratio is x increased or decreased when y is halved and z is doubled?

A. 4:1 increase
B. 2:1 increase
C. 1:1 no change
D. 1:4 decrease
E. 3:4 decrease

Question 7:

• JAMB 1983

If w varies inversely as V and U varies directly as w³, Find the relationship between u and v given that u = 1, when v = 2

A. U = \(\frac{8}{v^3}\)
B. V = \(\frac{8}{u^2v^3}\)
C. U = 8v³
D. V = 8u²

Question 8:

• JAMB 1984

p varies directly as the square of q and inversely as r. If p = 36, when q = 36, when q = 3 and r = 4, find p when q = 5 and r = 2

A. 72
B. 100
C. 90
D. 200
E. 125

Question 9:

• JAMB 1987

If P varies inversely as V and V varies directly as R², find the relationship between P and R given that R = 7 when P = 2

A. P = 98R²
B. PR² = 98
C. P = \(\frac{1}{98R^{2}}\)
D. P = \(\frac{PR^{2}}{98}\)

Question 10:

• JAMB 2013

P varies jointly as m and u, and varies inversely as q. Given that p = 4, m = 3 and u = 2 and q = 1, find the value of p when m = 6, u = 4 and q =\(\frac{8}{5}\)

A. 12\(\frac{8}{5}\)
B. 15
C. 10
D. 28\(\frac{8}{5}\)