6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

A boat travels 72 km downstream in 8 hours and 84 km upstream in 12 hours. Find the speed of the boat in still water and the speed of the water current ?

A) 9 and 3 kmph	B) 6 and 7 kmph
C) 8 and 1 kmph	D) 7 and 2 kmph

Answer & Explanation Answer: C) 8 and 1 kmph

Explanation:

Downstream speed = 72km/8hrs = 9 kmph
upstream speed = 84km/12hrs = 7 kmph
speed of boat = avg of downstream and upstream speeds
speed of boat = (9+7)/2kmph = 8 kmph.
current speed = half of the difference of downstream and upstream speeds
currend speed = (9-7)/2kmph = 1 kmph

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Filed Under: Boats and Streams
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19 8989

Q:

The average of a non-zero number and its square is 11 times the number. The number is ?

A) 22	B) 21
C) 11	D) 17

Answer & Explanation Answer: A) 22

Explanation:

Let the number be 'x'.

$\frac{x + x^{2}}{2}$ = 11x
$x^{2}$ = 22x
=> x = 22.

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Filed Under: Average
Exam Prep: GATE , CAT , Bank Exams
Job Role: Bank Clerk

8 8984

Q:

Running at the same constant rate, 6 identical machines can produce a total of 270 bottles per minute. At this rate, how many bottles could 10 such machines produce in 4 minutes?

A) 648	B) 1800
C) 2700	D) 10800

Answer & Explanation Answer: B) 1800

Explanation:

Let the required number of bottles be x.

More machines, More bottles (Direct Proportion)

More minutes, More bottles (Direct Proportion)

$\begin{array}{r} \begin{matrix} m a c h i n e s & 6 : 10 \end{matrix} \\ \begin{matrix} t i m e (i n m i n) & 1 : 4 \end{matrix} \end{array}\} ⋮ ⋮ 270 : x$

=> 6 * 1 * x = 10 * 4 * 270

=> x= 1800

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Filed Under: Chain Rule

3 8982

Q:

A group of men can complete a job in K hours. After every 4 hours, half the number of men working at that point of time leave the job. Continuing this way if the job is finished in 16 hours, what is the value of K ?

A) 7 hrs	B) 7.5 hrs
C) 8 hrs	D) 8.25 hrs

Answer & Explanation Answer: B) 7.5 hrs

Explanation:

Let there are L men

job requires LK man hours.

job completed in first 4 hrs = L x 4 = 4L

job completed in next 4 hrs = 4 x L/2 = 2L

job completed in next 4 hrs = 4 x L/4 = L

job completed in last 4 hrs = 4 x L/8 = L/2

4L + 2L + L + L/2 = KL

K = 7+1/2 = 7.5 hours.

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Filed Under: Time and Work
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5 8977

Q:

X can complete the work in 10 days, Y can do the same in 15 days. If they are hired for 5 days to do the work together, what is the work that left unfinished?

A) 1/3	B) 2/3
C) 1/6	D) 5/6

Answer & Explanation Answer: C) 1/6

Explanation:

Given X can do in 10 days

=> 1 day work of X = 1/10

Y can do in 15 days

=> 1 day work of Y = 1/15

1day work of (X + Y) = 1/10 + 1/15 = 1/6

Given they are hired for 5 days

=> 5 days work of (X + Y) = 5 x 1/6 = 5/6

Therefore, Unfinished work = 1 - 5/6 = 1/6

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Filed Under: Time and Work
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11 8948

Q:

Variance of the data 2, 4, 5, 6, 8, 17 is 23.33. Then the variance of 4, 8, 10, 12, 16, 34 will be

A) 11.66	B) 46.66
C) 93.3333	D) 4.83

Answer & Explanation Answer: C) 93.3333

Explanation:

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Filed Under: Probability
Exam Prep: Bank Exams

5 8940

Q:

In an election, there were two candidates only. The candidate who got 62% of the total votes polled and was elected by a majority of 192 votes. The total number of votes polled was?

Answer

Suppose total votes polled is x

$\inline \Rightarrow$ $\inline \frac{62x}{100}=\frac{38x}{100}+192$

$\inline \Rightarrow \frac{62x}{100}-\frac{38x}{100}=192$

$\inline \Rightarrow \frac{24x}{100}=192\Rightarrow x=800$

Workspace

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Subject: Percentage

57 8929

Q:

Three taps I, J and K can fill a tank in 20,30and 40 minutes respectively. All the taps are opened simultaneously and after 5 minutes tap A was closed and then after 6 minutes tab B was closed .At the moment a leak developed which can empty the full tank in 70 minutes. What is the total time taken for the completely full ?

A) 24.315 minutes	B) 26.166 minutes
C) 22.154 minutes	D) 24 minutes

Answer & Explanation Answer: B) 26.166 minutes

Explanation:

Upto first 5 minutes I, J and K will fill => 5[(1/20)+(1/30)+(1/40)] = 65/120

For next 6 minutes, J and K will fill => 6[(1/30)+(1/40)] = 42/120

So tank filled upto first 11 minutes = (65/120) + (42/120) = 107/120
So remaining tank = 13/120

Now at the moment filling with C and leakage @ 1/60 per minute= (1/40) - (1/70) = 3/280.
So time taken to fill remaining 13/120 tank =(13/120) /(3/280) = 91/6 minutes

Hence total time taken to completely fill the tank = 5 + 6 + 91/6 = 26.16 minutes.

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Filed Under: Pipes and Cistern
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13 8928

Quantitative Aptitude - Arithmetic Ability Questions

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