Arithmetic Q&A - Solve Basic Math Problems & Improve Skills

Q11 :

A sum of Rs. 6.25 is made up of 80 coins which are either 10 P or 5 P coins. The number of 10 P coins are

A

32

B

35

C

40

D

45

View Answer

Correct Answer: D

45

Description:

Check from the choice. Let 10 P coins be 45.

So that 5 P coins are 35

Total value = 10 $times$ 45 + 5 $times$ 35 = 625 P which is true

Q12 :

A positive number when decreased by 4 become 21 times its reciprocal. The number is

A

8

B

7

C

6

D

5

View Answer

Correct Answer: B

7

Description:

Let the number be $x$
Then $x-4=frac{21}{x} Rightarrow x^2-4x-21=0$

Rightarrow (x-7) (x+3)=0

$therefore x=7$

Q13 :

In an NCC camp of 300 cadets, there was enough food for 22 days. But as some more cadets joined the camp on the very first day, the food was exhausted in 20 days only. The number of cadets who joined later is

A

20

B

30

C

50

D

60

View Answer

Correct Answer: B

30

Description:

Given that the food is finished in 20 days by

$frac{300 times 22}{20} = 330 text{ cadets}$

$therefore$ 30 more cadets joined

Q14 :

The decimal number $0.overline{32}$ is equal to the rational number

A

$frac{32}{100}$

B

$frac{32}{99}$

C

$frac{30}{100}$

D

$frac{31}{99}$

View Answer

Correct Answer: B

$frac{32}{99}$

Description:

$text{ Let } x = 0.overline{32} = 0.323232...$

$therefore 100x = 32.323232...$

$= 32.overline{32} Rightarrow 99x = 32$

$therefore x = frac{32}{99}$

Q15 :

Which one of the following measures of central tendency gives greater importance to smaller and lesser importance to bigger items of a series?

A

Arithmetic mean

B

Geometric mean

C

Median

D

Mode

View Answer

Correct Answer: B

Geometric mean

Description:

Geometric mean gives the greater importance to smaller and lesser importance to bigger items of a series.

Q16 :

If the mean of five observations $x, x+ 2, x + 4, x + 6 text{ and } x + 8$ is 11. Then the mean of last three observations is

A

11

B

13

C

15

D

17

View Answer

Correct Answer: B

13

Description:

Mean of the given observations

$= x + 4 = 11 Rightarrow x = 7$

Required mean of the last three observations

$= x + 6 = 13$

Q17 :

The arithmetic mean of $n$ number is $overline{x}$ . The sum of the first $(n - 1)$ numbers is $k$ . The $n$ th number is

A

$n overline{x} - 2k$

B

$n overline{x} - k$

C

$n overline{x} + k$

D

$n overline{x} + 2k$

View Answer

Correct Answer: B

$n overline{x} - k$

Description:

The sum of $n$ number $= n ; overline { x}$ ,
any given sum of $(n - 1)text{th no. } = k$
$therefore text{ nth number } = n ; overline{x} - k$

Q18 :

If $frac{3}{4}$ of an estate is worth Rs. 90,000/-, then the value of $frac{2}{3}$ of the same will be

A

Rs. 60,000

B

Rs. 65,000

C

Rs. 70,000

D

Rs. 80,000

View Answer

Correct Answer: D

Rs. 80,000

Description:

The value of $frac{2}{3}$ rd estate is $= frac{90,000 times 4 times 2}{3 times 3}$

= Rs. 80,000/-

Q19 :

Let $n[text{X}]$ denote the number of elements in the set $text{X}$ . If for two sets A and B, $n$ [A] = 12, $n$ [B] = 30, $n$ [A $cap$ B] = 25, then $n$ [A $cup$ B] is equal to

A

25

B

19

C

17

D

15

View Answer

Correct Answer: C

17

Description:

Apply $n(A cup B) = n(text{A}) + n(text{B}) - n(text{A} cap text{B})$

Q20 :

The value of $frac{(.05 times .05 times .05) + (.04 times .04 times .04)}{(.05 times .05) - (.05 times .04) + (.04 times .04)}$ is

A

0.0009

B

0.01

C

0.09

D

0.41

View Answer

Correct Answer: C

0.09

Description:

Apply the formula $frac{a^3 + b^3}{a^2 - ab + b^2} = (a + b)$

where $a = 0.05 text{ and } b = 0.04$

Arithmetic Questions Answers