CDS Exam (II)- 2020 - Elementary Mathematics Defence Question Paper

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CDS Exam (II)- 2020 - Elementary Mathematics

CDS Exam (II)- 2020 - Elementary Mathematics Defence Questions

11.
If \( 17^{2020} \) is divided by 18, then what is the remainder?
A.
1
B.
2
C.
16
D.
17
ANSWER :
A. 1
12.
What is the value of
\( \frac{1}{1 + \sqrt{2}} + \frac{1}{\sqrt{2} + \sqrt{3}} + \frac{1}{\sqrt{3} + \sqrt{4}} + \ldots + \frac{1}{\sqrt{99} + \sqrt{100}} \)?
A.
1
B.
5
C.
9
D.
10
ANSWER :
C. 9
13.
If \( x^{m} = \sqrt[14]{x \sqrt{x \sqrt{x}}} \), then what is the value of m?
A.
\( \frac{1}{8} \)
B.
\( \frac{1}{4} \)
C.
\( \frac{3}{4} \)
D.
\( \frac{7}{4} \)
ANSWER :
A. \( \frac{1}{8} \)
14.
The sum of all possible products taken two at a time out of the numbers \( \pm 1, \pm 2, \pm 3, \pm 4, \pm 5 \) is
A.
0
B.
-30
C.
-55
D.
55
ANSWER :
C. -55
15.
A train of length 110 m is moving at a uniform speed of 132 km/hr. The time required to cross a bridge of length 165 m is
A.
6.5 seconds
B.
7 seconds
C.
7.5 seconds
D.
8.5 seconds
ANSWER :
C. 7.5 seconds
16.
The simple interest on a certain sum is one-fourth of the sum. If the number of years and the rate of annual interest are numerically equal, then the number of years is
A.
2.5
B.
3
C.
3.5
D.
5
ANSWER :
D. 5
17.
A 60-page book has n lines per page. If the number of lines were reduced by 3 in each page, the number of pages would have to be increased by 10 to give the same writing space. What is the value of n?
A.
18
B.
21
C.
24
D.
30
ANSWER :
B. 21
18.
If x men working x hours per day can do x units of work in x days, then y men working y hours per day in y days would be able to do k units of work. What is the value of k?
A.
\( x^{2}y^{-3} \)
B.
\( x^{3}y^{-2} \)
C.
\( y^{2}x^{-3} \)
D.
\( y^{3}x^{-2} \)
ANSWER :
D. \( y^{3}x^{-2} \)
19.
Let d(n) denote the number of positive divisors of a positive integer n. Which of the following are correct?
1. d(5) = d(11)
2. d(5).d(11) = d(55)
3. d(5) + d(11) = d(16)
Select the correct answer using the code given below:
A.
1 and 3 only
B.
1 and 2 only
C.
2 and 3 only
D.
1, 2 and 3
ANSWER :
B. 1 and 2 only
20.
If \( A_{n} = P_{n} + 1 \), where \( P_{n} \) is the product of the first n prime numbers, then consider the following statements:
1. \( A_{n} \) is always a composite number.
2. \( A_{n} + 2 \) is always an odd number.
3. \( A_{n} + 1 \) is always an even number.
Which of the above statements is/are correct?
A.
1 only
B.
2 only
C.
3 only
D.
2 and 3 only
ANSWER :
D. 2 and 3 only