2013 - JAMB Mathematics Past Questions and Answers - page 4

31
What is the probability that an integer x \((1 \leq x \leq 25)\) chosen at random is divisible by both 2 and 3?
A
\(\frac{1}{25}\)
B
\(\frac{1}{5}\)
C
\(\frac{4}{25}\)
D
\(\frac{3}{4}\)
correct option: c

((1 \leq x \leq 25)) = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25}

Number N of x divisible by both 2 and 3 is 4.

n((\varepsilon)) = 25

= (\frac{N}{n(\varepsilon)})

= (\frac{4}{25})

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32
A basket contains 9 apples, 8 bananas and 7 oranges. A fruit is picked from the basket, find the probability that it is neither an apple nor an orange.
A
\(\frac{3}{8}\)
B
\(\frac{1}{3}\)
C
\(\frac{7}{24}\)
D
\(\frac{2}{3}\)
correct option: b

n(apples) = 9

n(bananas) = 9

n(oranges) = 9

n((\varepsilon)) = 24

Hence Prob(not apple, nor orange) = Prob(banana) = (\frac{8}{24}) = (\frac{1}{3})

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33
The graph is shown is correctly represented by
A
y = x2 - x - 2
B
y = x2 - 3x + 2
C
y = x2 - x - 1
D
y = x2 + x - 2
correct option: a

The graph crosses the x-axis at x = -1 and x = 2

Thus, x + 1 = 0 and x - 2 = 0

x2 - 2x + x - 2 = 0

x2 - x - 2 = 0

giving y = x2 - x - 2

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34
In the diagram given, find the value of x.
A
30o
B
40o
C
45o
D
15o
correct option: b

In the diagram above, < CDE = < CED = 15o

(base < s of isos. (\bigtriangleup))

< ECD = 180o - (15 + 15)o

= 180o - 30o = 150o

But x + 110o = 150o

(Sum of opp. interior < s of a(\bigtriangleup) = opp. exterior < )

x = 150o - 110o = 40o

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35
The value x in the figure given is
A
110o
B
100o
C
70o
D
130o
correct option: d
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36
The bar chart above shows the allotment of time(in minutes) per week for selected subjects in a certain school. What is the total time allocated to the six subjects per week?
A
460mins
B
720mins
C
960mins
D
200mins
correct option: b

80 + 160 + 200 + 80 = 128 + 72 = 720minutes

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37
The pie chart above shows the statistical distribution of 80 students in five subjects in an examination. Calculate how many student offer Mathematics.
A
30
B
11
C
50
D
20
correct option: b

5xo + (16x - 24)o + 5xo + (4x + 12)o + (6x + 12)o = 360o

360xo - 24 + 12 + 12 = 360o

36xo = 360o

xo = (\frac{360^0}{36})

= 10o

Thus, the angle of sector representing Mathematics is 5 x 10o = 50o. Hence the number of students who offer mathematics is

(\frac{55^o}{36} \times 80 \approx 11)

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