1. Find the value of [latex]{676}^{2} - {33}^{2}.[/latex]
A. 3200
B. 3400
C. 3146
D. 3143
Answer - Option B
Explanation -
[latex]{676}^{2} - {33}^{2}[/latex] = (67 + 33) (67 – 33)
= 100 × 34 = 3400
2. Given that log 2 = 0.3 approx., one billion would be approx
A. [latex]{2}^{9}[/latex]
B. [latex]{2}^{10}[/latex]
C. [latex]{2}^{20}[/latex]
D. [latex]{2}^{30}[/latex]
Answer - Option D
Explanation -
1 billion = [latex]{10}^{9}[/latex]
Let [latex]{10}^{9}[/latex] = [latex]{2}^{N}[/latex]
Taking log both sides we get,
9 lot 10 = n log 2
9 = n × 0.3
n = 30
3. In how many different ways can 3 identical white balls and 2 identical red balls be arranged besides each other, in a straight line?
Answer - Option B
Explanation -
Required number of ways
[latex]\frac{5!}{3! * 2!}[/latex] = 10
4. What is the probability of getting 3 aces if three cards are drawn from a set of 52 playing cards?
A. [latex]{52}^{3}[/latex]
B. [latex]\frac{1}{{52}^{3}}[/latex]
C. [latex]\frac{1}{52!}[/latex]
D. [latex]\frac{4 * 3 * 2}{52 * 51 * 50}[/latex]
Answer - Option D
Explanation -
Required probability
[latex]\frac{^{4}{C}_{3}}{^{52}{C}_{3}}[/latex] = [latex]\frac{4 * 3 * 2}{52 * 51 * 50}[/latex]
5. In a class of 40 students, 25 are sports persons and 25 are mathematicians. What is the probability that the monitor of the class is both a sports person and a mathematician?
A. [latex]\frac{1}{40}[/latex]
B. [latex]\frac{1}{25}[/latex]
C. [latex]\frac{1}{4}[/latex]
D. [latex]\frac{1}{50}[/latex]
Answer - Option C
Explanation -
Number of boys who are both sports person and a mathematician = 254 + 25 – 10 = 40
Hence, required probability = [latex]\frac{10}{40} = \frac{1}{4}[/latex]
6. Sum of two numbers is 15 and sum of their reciprocals is [latex]\frac{15}{56}[/latex]. The two numbers are
A. 4, 11
B. 5, 10
C. 6, 9
D. 7, 8
Answer - Option D
Explanation -
a + b = 15 and [latex]\frac{1}{a} + \frac{1}{b} = \frac{15}{56}[/latex]
[latex]\frac{a + b}{ab} = \frac{15}{56}[/latex]
(a, b) = (7, 8)
7. If α, β are the roots of quadratic equation [latex]{x}^{2}[/latex]+ x + 1 = 0 , then [latex]\frac{1}{α}+ \frac{1}{β}[/latex] is
A. -1
B. 1
C. 0
D. None of these
Answer - Option A
Explanation -
[latex]\frac{1}{α} + \frac{1}{β} = \frac{α + β}{αβ}[/latex]
given, α + β = –1 and αβ = 1
Hence, [latex] \frac{α + β}{αβ} = \frac{-1}{1} = -1[/latex]
8. Value of [latex]\sqrt{6 + \sqrt{6 +\sqrt{6 + .....}}}[/latex] is
A. [latex]\frac{5}{2}[/latex]
B. -2
C. 3
D.4
Answer - Option C
Explanation -
[latex]\sqrt{6 + \sqrt{6 +\sqrt{6 + .....}}}[/latex] = x
squaring both sides we get,
6 + x = [latex]{x}^{2}[/latex]
x = 3
9. If a, b, c, d, e and f are in arithmetic progression, then e – c is equal to
A. 2(b – a)
B. c – b
C. 2 (f – d)
D. 2(d – b)
Answer - Option A
e – c = (e – d) + (d – c)
= 2(b – a)
10. Find the median of the following numbers : 14, 23, 20, 12, 11, 15, 24, 17, 9, 21, 25
Answer - Option C
14, 23, 20, 12, 11, 15, 24, 17, 9, 21, 25
When written in ascending order becomes: 9, 11, 12, 14, 15, 17, 20, 21, 23, 24, 25
Hence, median or mid-term = 17
11. A student was asked to multiply a number by 12. By mistake he multiplied the number by 21 and got the answer 63 more than the correct answer. What is the correct answer?
Answer - Option D
Explanation -
set the number be x.
x × 21 = x + 12 + 63
x = 7
Hence, correct answer = 12 × 7 = 84
12. Find the value of [latex]\frac{{768}^{3} + {232}^{3}}{{768}^{2} - (768 * 232) + {232}^{2}}[/latex]
A. 1000
B. 536
C. 500
D. 268
Answer - Option A
Explanation -
[latex]\frac{{768}^{3} + {232}^{3}}{{768}^{2} - (768 * 232) + {232}^{2}}[/latex]
[latex] (768 + 232)(\frac{{768}^{2} + {232}^{2}}){{768}^{2} - (768 * 232) + {232}^{2}}[/latex]
= 768 + 232
= 1000
13. Find the value of (1 + 2 + 3 + 4 +..........+ 45) :
A. 2140
B. 2070
C. 1035
D. 1280
Answer - Option C
Explanation -
Required sum = (1 + 4S) ×45
= 23 × 4S - 1035
14. In an examination, a student gets 4 marks for every correct answer and loses 1 mark for even' wrong answer. If he attempts in all 60 questions and secures 130 marks, then find the number of questions he attempted correctly.
Answer - Option D
Explanation -
set the no. of correct questions be x
x × 4 – (60 – x) × 1 = 130
Sx – 60 = 130
x = 38
15. If [latex]\frac{x}{y} = \frac{6}{5}[/latex], then find the value of [latex]\frac{{x}^{2} + {y}^{2}}{{x}^{2} - {y}^{2}}[/latex]:
A. 11
B. [latex]\frac{61}{11}[/latex]
C. [latex]\frac{11}{5}[/latex]
D. 6
Answer - Option B
Explanation -
[latex]\frac{x}{y} = \frac{6}{5}[/latex]
[latex]\frac{{x}^{2} + {y}^{2}}{{x}^{2} - {y}^{2}}[/latex] = [latex]\frac{{6}^{2} + {5}^{2}}{{6}^{2} - {5}^{2}}[/latex] = [latex]\frac{61}{11}[/latex]