Quantitative Aptitude - Arithmetic Ability Questions

Q:

A research team of 6 people is to be formed from 10 chemists,5 politicians, 8 economists and 15 biologists.How many teams have atleast 5 chemists?

A) 7350 B) 6400
C) 6379 D) 7266
 
Answer & Explanation Answer: D) 7266

Explanation:

10C5*28C1*10C6 = 7266

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Q:

After working for 8 days, Hari Ram finds that only 1/3 rd of the work has been done. He employs Satya who is 60% as efficient as Hari Ram. How many days more would Satya take to complete the work ?

A) 24 1/2 days B) 25 3/2 days
C) 24 2/3 days D) 26 2/3 days
 
Answer & Explanation Answer: D) 26 2/3 days

Explanation:

1/3 ---- 8

1 -------?
Hari can do total work in = 24 days

As satya is 60% efficient as Hari, then

Satya = 1/24 x 60/100 = 1/40

=> Satya can do total work in 40 days

1 ----- 40

2/3 ---- ? => 26 2/3 days.

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Q:

A number is selected at random from the numbers 1 to 30. What is the probability that it is divisible by either 3 or 7 ?

A) 1/30 B) 2/30
C) 1/25 D) 1/2
 
Answer & Explanation Answer: A) 1/30

Explanation:

Let A be event of selecting a number divisible by 3. B be the event of selecting a number divisible by 7.

  Proability tutorial

 A = { 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 }, so n(A)=10
 B = { 7, 14, 21, 28 }, n(B)= 4 

Probability problems 

Since A and B are not mutually exclusive So :

Probability addition rule

Probability problems

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Q:

A rectangular park 60 m long and 40 m wide has two concrete crossroads running in the middle of the park and rest of the park has been used as a lawn. If the area of the lawn is 2109 sq. m, then what is the width of the road?

A) 2.91 m B) 3 m
C) 5.82 m D) None of these
 
Answer & Explanation Answer: B) 3 m

Explanation:

Area of the park = (60 x 40) = 2400 sq.m  

Area of the lawn = 2109  sq.m 

Area of the crossroads = (2400 - 2109) = 291 sq.m   

 

Let the width of the road be x metres. Then,   

60x + 40x - (x * x) = 291  

=>(x * x) - 100x + 291 = 0    

=>(x - 97)(x - 3) = 0  

=>x=3

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Q:

Last year vivek saved 10% of his annual earnings, this year he earned 5% more than last year and he saved 12% of his annual earnings. The amount saved this year was what percentage of the amount saved last year ?

A) 87% B) 98%
C) 138% D) 126%
 
Answer & Explanation Answer: D) 126%

Explanation:

Suppose total earnings = Rs. 10000
10% saving = 10000 x (10/100) = Rs. 1000
This year 5% more income than prev year = Rs. 10500
12% saving = 10500 x (12/100) = Rs. 1260
Percentage of amount saved = (1260/1000) x 100 = 126%

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4 7202
Q:

The letters of the word PROMISE are to be arranged so that three vowels should not come together. Find the number of ways of arrangements?

A) 4320 B) 4694
C) 4957 D) 4871
 
Answer & Explanation Answer: A) 4320

Explanation:

Given Word is PROMISE.

Number of letters in the word PROMISE = 7

Number of ways 7 letters can be arranged = 7! ways

Number of Vowels in word PROMISE = 3 (O, I, E)

Number of ways the vowels can be arranged that 3 Vowels come together = 5! x 3! ways

 

Now, the number of ways of arrangements so that three vowels should not come together

= 7! - (5! x 3!) ways = 5040 - 720 = 4320.

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Filed Under: Permutations and Combinations
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Q:

12 boys decided to constribute Rs. 750 each to an Orphange. Suddenly few of them boys dropped out and consequently the rest had to pay Rs. 150 more. Then the number of boys who dropped out?

A) 4 B) 6
C) 2 D) 3
 
Answer & Explanation Answer: C) 2

Explanation:

Total money decided to contribute = 750 x 12 = 9000

Let 'b' boys dropped

The rest paid 150/- more

=> (12 - b) x 900 = 9000

=> b = 2

Hence, the number of boys who dropped out is 2.

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26 7187
Q:

The probabilities that drivers A, B and C will drive home safely after consuming liquor are 2 / 5, 3 / 7 and 3 / 4, respectively. What is the probability that they will drive home safely after consuming liquor ?

A) 3/70 B) 4/70
C) 9/70 D) 1/50
 
Answer & Explanation Answer: C) 9/70

Explanation:

Let A be the event of driver A drive safely after consuming liquor. 

 

Let B be the event of driver B drive safely after consuming liquor. 

 

Let C be the event of driver C drive safely after consuming liquor. 

 

P(A)=2/5,P(B)=3/7,P(C)=3/4

 

The events A, B and C are independent . Therefore,

 

PABC=P(A)P(B)P(C)=25*37*34=970

 

Therefore, The probability that all the drivers will drive home safely after consuming liquor is 9/70

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