6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

A box contains 10 bulbs,of which just three are defective. If a random sample of five bulbs is drawn, find the probability that the sample contains exactly one defective bulb.

A) 5/12	B) 7/12
C) 3/14	D) 1/12

Answer & Explanation Answer: A) 5/12

Explanation:

Total number of elementary events = $10 C_{5}$

Number of ways of selecting exactly one defective bulb out of 3 and 4 non-defective out of 7 is $3 C_{1} * 7 C_{4}$

So,required probability = $3 C_{1} * 7 C_{4}$ / $10 C_{5}$ = 5/12.

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Filed Under: Probability

66 35346

Q:

Find the total surface area (in cm2) of a hemisphere of diameter 21 cm.

A) 1039.5	B) 844.5
C) 637	D) 472

Answer & Explanation Answer: A) 1039.5

Explanation:

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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams

2 35302

Q:

A container contains 50 litres of milk. From that 8 litres of milk was taken out and replaced by water. This process was repeated further two times. How much milk is now contained by the container ?

A) 24.52 litres	B) 29.63 litres
C) 28.21 litres	D) 25.14 litres

Answer & Explanation Answer: B) 29.63 litres

Explanation:

Given that container has 50 litres of milk.

After replacing 8 litres of milk with water for three times, milk contained in the container is:

$\Rightarrow [50 {(1 - \frac{8}{50})}^{3}]$

$\Rightarrow (50 \times \frac{42}{50} \times \frac{42}{50} \times \frac{42}{50})$ = 29.63 litres.

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Filed Under: Alligation or Mixture
Exam Prep: CAT
Job Role: Bank PO

51 35269

Q:

Consider the following grouped frequency distribution:

x f

0-10 8

10-20 12

20-30 10

30-40 p

40-50 9

If the mean of the above data is 25.2, then what is the value of p?

A) 9	B) 10
C) 11	D) 12

Answer & Explanation Answer: C) 11

Explanation:

Mean = (sum of fixi/ (sum of f) = (8*5 + 12*15 + 10*25 + P*35 +9*45) / (8+12+10+P+9) = 25.2

(875 + 35P)/(39+P) = 25.2

P = 11

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Filed Under: Average
Exam Prep: Bank Exams

0 35189

Q:

A man buys Rs. 20 shares paying 9% dividend. The man wants to have an interest of 12% on his money. The market value of each share is:

A) 12	B) 15
C) 18	D) 20

Answer & Explanation Answer: B) 15

Explanation:

Dividend on Rs. 20 = Rs. (9/100)x 20 = Rs.9/5.

Rs. 12 is an income on Rs. 100.

Rs.9/5 is an income on Rs.[ (100/12) x (9/5)] = Rs. 15.

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Filed Under: Stocks and Shares

41 35055

Q:

A father left a will of Rs.35 lakhs between his two daughters aged 8.5 and 16 such that they may get equal amounts when each of them reach the age of 21 years. The original amount of Rs.35 lakhs has been instructed to be invested at 10% p.a. simple interest. How much did the elder daughter get at the time of the will?

A) 17.5 lakhs	B) 21 lakhs
C) 15 lakhs	D) 20 lakhs

Answer & Explanation Answer: B) 21 lakhs

Explanation:

Let Rs.x be the amount that the elder daughter got at the time of the will. Therefore, the younger daughter got (3,500,000 - x).

The elder daughter’s money earns interest for (21 - 16) = 5 years @ 10% p.a simple interest.

The younger daughter’s money earns interest for (21 - 8.5) = 12.5 years @ 10% p.a simple interest.

As the sum of money that each of the daughters get when they are 21 is the same,

$x + \frac{5 * 10 * x}{100} = (3, 500, 000 - x) + \frac{12.5 * 10 * (3, 500, 000 - x)}{100}$

$x + \frac{50}{x} = 3, 500, 000 - x + \frac{125}{100} * 3, 500, 000 - \frac{125 x}{100}$

$2 x + \frac{50 x}{100} + \frac{125 x}{100} = 3, 500, 000 * (1 + \frac{5}{4})$

$\frac{200 x + 50 x + 125 x}{100} = \frac{9}{4} * (3, 500, 000)$

=> $x = 2, 100, 000 = 21 l a k h s$

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Filed Under: Simple Interest
Exam Prep: GRE

57 34916

Q:

Find the average of first 20 multiples of 9.

A) 94.8	B) 94.7
C) 94.6	D) 94.5

Answer & Explanation Answer: D) 94.5

Explanation:

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Filed Under: Average
Exam Prep: Bank Exams

1 34780

Q:

The diagonal of a rectangle is $\sqrt{41}$ cm and its area is 20 sq. cm. The perimeter of the rectangle must be:

A) 18	B) 28
C) 38	D) 48

Answer & Explanation Answer: A) 18

Explanation:

$\sqrt{(l^{2} + b^{2})} = \sqrt{41}$ (or) $l^{2} + b^{2} = 41$

Also, $l b = 20$

${(l + b)}^{2} = l^{2 +} b^{2} + 2 l b$ = 41 + 40 = 81

(l + b) = 9.

Perimeter = 2(l + b) = 18 cm.

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Filed Under: Area
Exam Prep: CAT , Bank Exams , AIEEE
Job Role: Bank PO , Bank Clerk

129 34776

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