2008 - JAMB Mathematics Past Questions and Answers - page 9
81
What is the mean of the data t, 2t - 1, t - 2, 2t - 1, 4t and 2t + 2?
A
2t
B
2t - 1
C
\(\frac{2}{3}\)t + 1
D
2t - \(\frac{1}{3}\)
correct option: d
\(\frac{t + 2t - 1 + t - 2 + 2t - 1 + 4t + 2t + 2}{6}\)
= \(\frac{12t - 2}{6}\)
= \(\frac {12t}{6}\) - \(\frac{2}{6}\)
= 2t - \(\frac{1}{3}\)
Users' Answers & Comments= \(\frac{12t - 2}{6}\)
= \(\frac {12t}{6}\) - \(\frac{2}{6}\)
= 2t - \(\frac{1}{3}\)
82
What is the median of 4, 1, 4, 1, 0, 4, 4, 2 and 0
A
o
B
1
C
2
D
4
83
If x > 0, find the range of the numbers x - 3, 3x + 2, x - 1, 4x, 2x - 1, x - 2, 2x - 2, 3x and 3x + 1
A
3x + 3
B
3x + 1
C
2x + 5
D
2x + 1
84
Find the mean deviation of 2, 4, 5 and 9
A
1
B
2
C
5
D
7
correct option: b
\(\begin{array}{c|c} x & f & fx & x - \bar{x} & f(x - \bar{x}) \ \hline 2 & 1 & 2 & -3 & -3 & 3\ 4 & 1 & 4 & -1 & 1 & 1\ 5 & 1 & 5 & 0 & 0 & 0 \9 & 1 & 9 & 4 & 4 & 4 \ \hline & 4 & 20 & & & 8 \end{array}\)
x = \(\frac{\sum fx}{\sum fx}\)
= \(\frac{20}{4}\)
= 5
MD = \(\frac{\sum f(x - \bar{x})}{\sum f}\)
= \(\frac{8}{4}\)
= 2
Users' Answers & Commentsx = \(\frac{\sum fx}{\sum fx}\)
= \(\frac{20}{4}\)
= 5
MD = \(\frac{\sum f(x - \bar{x})}{\sum f}\)
= \(\frac{8}{4}\)
= 2
85
In how many ways can the letters of the word ACCEPTANCE be arranged?
A
\(\frac{10!}{2!2!3!}\)
B
\(\frac{10!}{2!3!}\)
C
\(\frac{10!}{2!2!}\)
D
\(\frac{10!}{3!2!2!}\)
86
Find the number of ways of selecting 6 out of 10 subjects for an examination
A
218
B
216
C
215
D
210
correct option: d
\(^{10}C_{6}\)
\(\frac{10!}{(n - r)!r!}\)
n = 10, r = 6
= \(\frac{10!}{(10 - 6)!6!}\)
= \(\frac{10!}{4!6!}\)
= \(\frac{10 \times 9 \times 8 \times 7}{4 \times 3 \times 2 \times 1}\)
= 5 x 3 x 2 x 7
= 210
Users' Answers & Comments\(\frac{10!}{(n - r)!r!}\)
n = 10, r = 6
= \(\frac{10!}{(10 - 6)!6!}\)
= \(\frac{10!}{4!6!}\)
= \(\frac{10 \times 9 \times 8 \times 7}{4 \times 3 \times 2 \times 1}\)
= 5 x 3 x 2 x 7
= 210
87
The probability of picking a letter T from the word OBSTRUCTION is
A
\(\frac{1}{11}\)
B
\(\frac{2}{11}\)
C
\(\frac{3}{11}\)
D
\(\frac{4}{11}\)
88
The result of rolling a fair die 150 times is as summarized in the table given.\(\begin{array}{c|c} Number & 1 & 2 & 3 & 4 & 5 & 6 \ \hline Frequency & 12 & 18 & x & 30 & 2x & 45\end{array}\)
What is the probability of obtaining a 5?
What is the probability of obtaining a 5?
A
\(\frac{3}{10}\)
B
\(\frac{1}{5}\)
C
\(\frac{1}{6}\)
D
\(\frac{1}{10}\)
correct option: b
\(\begin{array}{c|c}Number & 1 & 2 & 3 & 4 & 5 & 6 \ \hline Frequency & 12 & 18 & x & 30 & 2x & 45\end{array}\)
12 + 18 + x + 30 + 2x + 45 = 150
3x + 105 = 150
3x = 150 - 105
3x = 45
x = \(\frac{45}{3}\)
x = 15
probability of 5 = \(\frac{30}{150}\)
= \(\frac{1}{5}\)
Users' Answers & Comments12 + 18 + x + 30 + 2x + 45 = 150
3x + 105 = 150
3x = 150 - 105
3x = 45
x = \(\frac{45}{3}\)
x = 15
probability of 5 = \(\frac{30}{150}\)
= \(\frac{1}{5}\)
89
A
100o
B
80o
C
50o
D
30o
correct option: b
50 + 30 + y = 180
80 + y = 180
y = 100
180 + x = 180o
x = 180o - 100o
x = 80o
Users' Answers & Comments80 + y = 180
y = 100
180 + x = 180o
x = 180o - 100o
x = 80o
90
A
90o
B
53o
C
36o
D
26o