Problems on Numbers Quiz Set 004

Question 1

The sum of three consecutive even integer numbers is -2274. The middle among the three is?

A

-758.

B

-757.

C

-755.

D

-756.

Soln.
Ans: a

Let the numbers be 2n - 2, 2n and 2n + 2. The sum is 6n = 3 x 2n = 3 x middle. We are given 3 x middle = -2274, ⇒ middle = \$-2274/3\$, i.e., middle = -758.

Question 2

If \$2{3/8}\$ of a number is 3, what is \$1{1/35}\$ of that number?

A

\$1{199/665}\$.

B

\$2{201/664}\$.

C

\${199/667}\$.

D

\$4{191/667}\$.

Soln.
Ans: a

Let the number be N. Then it is given that \$2{3/8}\$ x N = 3. ⇒ N = 3 X \${8/19}\$. ⇒ \${36/35}\$ x N = \${36/35}\$ x 3 X \${8/19}\$ = \${864/665}\$.

\${19/8}\$ is same as \$2{3/8}\$. \${36/35}\$ is same as \$1{1/35}\$. \${864/665}\$ is same as \$1{199/665}\$.

Question 3

Which term of this arithmetic series is zero: 133, 126, 119 ...?

A

20.

B

21.

C

19.

D

22.

Soln.
Ans: a

The first term is 133, common difference is d = -7, n-th term is 0. So \$0 = 133 + (n - 1) × -7\$ which gives \$n = 1 + {133/7} = 20\$.

Question 4

If \$14/17\$ of a number is 84, what is the number?

A

102.

B

103.

C

101.

D

104.

Soln.
Ans: a

Let the number be N. Then \${14/17}\$ x N = 84. ⇒ N = 84 x \${17/14}\$ = 102

Question 5

The difference between a two digit number and the one obtained by reversing its digits is 81. If one of the digits is 5, what is the other?

A

Cannot exist.

B

5.

C

6.

D

7.

Soln.
Ans: a

Let the numbers be a and b. ab = 10a + b, and ba = 10b + a. The difference is 10a + b - (10b + a) = 9(a - b). It is given that 9(a - b) = 81, ⇒ a - b = \$81/9\$ = 9, ⇒ the difference between the digits is 9. If one of the digits is 5, the other cannot be determined.