2001 - JAMB Mathematics Past Questions and Answers - page 5

41
Find the range of these fractions:
1/6, 1/3, 3/2, 2/3, 8/9 and 4/3.
A
3/4
B
5/6
C
7/6
D
4/3
correct option: d

Using the L.C.M of the fractions, convert them to uniform base.

L.C.M = 36, the new fraction becomes: 6/36, 12/36, 54/36, 24/36, 32/36 and 48/36.

Range = highest value - lowest value

Highest among the given fraction = 54/36

Lowest among the given fraction = 6/36.

Range = (54/36) - (6/36) = 48/36 = 4/3

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42
Find the square pf the mode
A
49
B
121
C
25
D
64
correct option: b

Mode = 11

Square of the mode = 112

=121

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43
The mean score is
A
7.0
B
8.7
C
9.5
D
11.0
correct option: b

Mean ((43) + (75) + (82) + (117) + (132) + (81))/20

(12 + 35 + 16 + 77 + 26 + 8)/20

174/20 = 8.7

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44
Team P and Q are involved in a game of football.What is the probability that the game ends in a draw?
A
2/3
B
1/2
C
1/3
D
1/4
correct option: d

P(Games ends in draw)

This implies that Team P and Q wins

P(P wins) = 1/2
P(Q wins) = 1/2

P(game ends in a draw) = 1/2*1/2 = 1/4

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45
The distribution of colours of beads in a bowl is given above. What is the probability that a bead selected at random will be blue or white?
A
7/15
B
2/5
C
1/3
D
1/15
correct option: c

Total number of beads

= 1+2+4+5+3

=15

Number of blue beads = 1

P(Blue beads) = 1/15

Numbers of white beads = 4

P(white beads) = 4/15

∴P(Blue of white beads)

= P(Blue) + P(White)

= 1/15 + 4/15

= 5/15

= 1/3

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46
Find the variance of 2, 6, 8, 6, 2 and 6
A
6
B
5
C
√6
D
√5
correct option: b

mean of X = x = (2+6+8+6+2+6)/6 = 30/6 = 5

X → 2,6,8,6,2,6

X - x = -3, 1, 3, 1, 3, 1

(X - x)2 = 9, 1, 9, 1, 9, 1

∑(X-x) = 9+1+9+1+9+1 = 30

Variance = ∑(X-x)2/n = 30/6 = 5

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47
Find the number of ways of selecting 8 subjects from 12 subjects for an examination
A
490
B
495
C
496
D
498
correct option: b

Combination is the number (n) of ways of selecting a number of (m) of objects from n

(^{12}C_{8}\frac{12!}{8!(12-8)!}=\frac{12!}{8!4!}\frac{(12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 1)}{8\times 7\times 6\times 5\times 4\times 3\times 2\times 1}\After\hspace{1mm} cancelling \hspace{1mm}out \hspace{1mm}we\hspace{1mm} have\11\times 5\times 9 = 495 )

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48
Find the range of 1/6, 1/3, 3/2, 2/3, 8/9 and 4/3
A
3/4
B
5/6
C
7/6
D
4/3
correct option: d

1/6, 1/3, 3/2, 2/3, 8/9 and 4/3

L.C.M of the denominators = 36

The fraction now becomes

6/36, 12/36, 54/36, 24/36, 32/36 and 48/36

Highest fraction = 54/36

Lowest fraction = 6/36

Range = Highest - Lowest

(54/36) - (6/36)

= 48/36

= 4/3

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49
Triangle SPT is the solution of the linear inequalities
A
2y - x - 2 ≤ 0, y + 2x + 2 ≥ 0, -2 ≤ x ≤ - 1
B
-2 ≤ x ≤ 2, y ≥ 0, y + 2x + 2 ≤ 0, x ≤ 0
C
2y - x - 2 ≤ 0, y + 2x + 2 ≤ 0, y ≥ 0, x ≤ 0
D
2y - x - 2 ≥ 0, y + 2x + 2 ≤ 0, x ≤ 0
correct option: a

Δ SPT is the solution of the inequalities

2y - x - 2 ≤ 0

2y ≤ 2 + x

y ≤ 2/2 + x/2

y ≤ 1 + 1/2x

y + 2x + 2 ≥ 0,

y ≥ -2 -2x

∴ the solution of the inequalities

2y - x - 2 ≤ 0,

y + 2x + 2 ≥ 0

= -2 ≤ x ≤ -1

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50
klm
klmk
lmkl
mklm

The identity element with respect to the multiplication shown in the table above is
A
o
B
m
C
l
D
k
correct option: b
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