Variation - Jamb Mathematics Past Questions and Answers

Question 21:

• 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 22:

• JAMB 1983

y varies partly as the square of x and partly as the inverse of the square root of x.Write down the expression for y if y = 2 when x = 1 and y = 6 when x = 4

A. Y = \(\frac{10x^2}{31} + \frac{52}{31\sqrt{x}}\)
B. Y = x² + \(\frac{1}{\sqrt{x}}\)
C. Y = x² + \(\frac{1}{x}\)
D. Y = \(\frac{x^2}{31} + \frac{1}{31\sqrt{x}}\)

Question 23:

• 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 24:

• 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 25:

• JAMB 1985

In a restaurant, the cost of providing a particular type of food is partly constant and partially inversely proportional to the number of people. If cost per head for 100 people is 30k and the cost for 40 people is 60k, Find the cost for 50 people?

A. 15k
B. 20k
C. 50k
D. 40k
E. 45k