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JAMB Mathematics Past Questions & Answers - Page 296

1,476.

$\begin{array}{c|c} \text{Average hourly earnings(N)} & 5 - 9 & 10 - 14 & 15 - 19 & 20 - 24\\ \hline \text{No. of workers} & 17 & 32 & 25 & 24\end{array}$

Estimate the mode of the above frequency distribution

12.2

12.27

12.9

13.4

View answer & explanation

Correct answer is B

$\begin{array}{c|c} \text{Class intervals} & F & \text{Class boundary}\\ \hline 5 - 7 & 17 & 4.5 - 9.5\\ 10 - 14 & 32 & 9.5 - 14.5\\ 15 - 19 & 25 & 14.5 - 19.5\\ 20 - 24 & 24 & 19.5 - 24.5 \end{array}$

mode = 9.5 + $\frac{D_1}{D_2 + D_1}$ x C

= 9.5 + $\frac{5(32 - 17)}{2(32) - 17 - 25}$

= 9.5 + $\frac{75}{27}$

= 12.27

$\approx$ 12.3

1,477.

If m and n are the mean and median respectively of the set of numbers 2, 3, 9, 7, 6, 7, 8, 5, find m + 2n to the nearest whole number

View answer & explanation

Correct answer is A

mean(x) = $\frac{\sum x}{N}$

= $\frac{48}{8}$

= 5.875

re-arranging the numbers;

2, 3, 5, 6, 2, 7, 8, 9

median = $\frac{6 + 7}{2}$

= $\frac{1}{2}$

= 6.5

m + 2n = 5.875 + (6.5)²

= 13 + 5.875

= 18.875

= $\approx$ = 19

1,478.

find the equation of the curve which passes through by 6x - 5

6x² - 5x + 5

6x² + 5x + 5

3x² - 5x - 5

3x² - 5x + 3

View answer & explanation

Correct answer is D

m = $\frac{dy}{dv}$ = 6x - 5

∫dy = ∫(6x - 5)dx

y = 3x² - 5x + C

when x = 2, y = 5

∴ 5 = 3(2)² - 5(2) +C

C = 3

∴ y = 3x² - 5x + 3

1,479.

Evaluate ∫ $^{\pi}_{2}$ (sec² x - tan²x)dx

$\frac{\pi}{2}$

$\pi$ - 2

$\frac{\pi}{3}$

$\pi$ + 2

View answer & explanation

Correct answer is B

∫ $^{\pi}_{2}$ (sec² x - tan²x)dx

∫ $^{\pi}_{2}$ dx = [X] $^{\pi}_{2}$

= $\pi$ - 2 + c

when c is an arbitrary constant of integration

1,480.

Differentiate $\frac{x}{cosx}$ with respect to x

1 + x sec x tan x

1 + sec² x

cos x + x tan x

x sec x tan x + secx

View answer & explanation

Correct answer is D

let y = $\frac{x}{cosx}$ = x sec x

y = u(x) v (x0

$\frac{dy}{dx}$ = U $\frac{dy}{dx}$ + V $\frac{du}{dx}$

dy x [secx tanx] + secx

x = x secx tanx + secx