Quantitative aptitude Question for all banking Bank PO,Clerk,IBPS PO,Railway,SSC,PSUs,IAS,OAS ,C-SAT Exams 

Mathmetics

ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams

Q531.
Two dice are thrown simultaneously. What is the probability of getting two numbers whose product is even?

1) 1/2 2) 1/3
3) 3/4 4) 4/5
5)None of thesae
Answer : 3/4
Explanation :
In a simultaneous throw of two dice, we have n(S) = (6 x 6) = 36.

Then, E =  {(1, 2), (1, 4), (1, 6), (2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (3, 2), (3, 4), (3, 6), (4, 1),
 (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (5, 2), (5, 4), (5, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)}
 n(E) = 27.

So, P(E) = n(E) / n(S) =27 /36 = 3/4

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Q532.
In a class, there are 15 boys and 10 girls. Three students are selected at random. The probability that 1 girl and 2 boys are selected, is:

1) 1/24 2) 21/46
3) 1/48 4) 24/117
5)None of these
Answer : 21/46
Explanation :
Let S be the sample space and E be the event of selecting 1 girl and 2 boys.

Then, n(S) = 25C3 =  Number ways of selecting 3 students out of 25

= (25 x 24 x 23) / (3 x 2 x 1) = 2300.
n(E) = (10C1 x 15C2)
= 10 x (15 x 14) /(2 x 1) = 1050.
So,  P(E) = n(E) / n(S) =1050 / 2300 =21/46 

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Q533.
Three unbiased coins are tossed. What is the probability of getting at most two heads ?
1) 1/4 2) 3/4
3) 7/8 4) 1/36
5)None of these
Answer : 7/8
Explanation :
Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}

Let E = Event of getting at most two heads.

Then E = {TTT, TTH, THT, HTT, THH, HTH, HHT}.

So, P(E) = n(E) / n(S) =7 /8 .

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Q534.
What is the probability of getting a sum 9 from two throws of a dice ?

1) 1/6 2) 1/8
3) 1/9 4) 1/12
5)None of these
Answer : 1/9
Explanation :
In two throws of a die, n(S) = (6 x 6) = 36.

Let E = event of getting a sum ={(3, 6), (4, 5), (5, 4), (6, 3)}.

So,P(E) = n(E) / n(S) = 4 /36 =1/9.

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Q535.
How many words with or without meaning, can be formed by using all the letters of the word, 'DELHI' using each letter exactly once ?
1) 60 2) 120
3) 180 4) 240
5)None of these
Answer : 120
Explanation :
The word 'DELHI' has 5 letters and all these letters are different.

Total words (with or without meaning) formed by using all these 5 letters using each letter exactly once

= Number of arrangements of 5 letters taken all at a time =  5P5 = 5! = 5 x 4 x 3 x 2 x 1 = 120
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Q536.
In how many ways can the letters of the word 'LEADER' be arranged ?
1) 60 2) 120
3) 240 4) 360
5)None of these
Answer : 360
Explanation :
The word 'LEADER' has 6 letters. 

But in these 6 letters, 'E' occurs 2 times and rest of the letters are different.

Hence,number of ways to arrange these letters = 6!2!=6×5×4×3×2×12×1 = 360
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Q537.
There are 8 men and 10 women and you need to form a committee of 5 men and 6 women. In how many ways can the committee be formed ?

1) 8750 2) 10420
3) 11760 4) 12420
5)None of these
Answer : 11760
Explanation :
We need to select 5 men from 8 men and 6 women from 10 women

Number of ways to do this  = 8C5 x 10C6

=  8C3 x 10C4 [Applied the formula nCr = nC(n - r) ]

= (8×7×63×2×1) (10×9×8×74×3×2×1)

= 56 x 210 = 11760
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Q538.
Out of 7 consonants and 4 vowels, how many words of 3  consonants and 2 vowels can be formed ?

1) 2100 2) 24400
3) 21300 4) 25200
5)None of these
Answer : 25200
Explanation :
Number of ways of selecting 3 consonants out of 7 = 7C3

Number of ways of selecting 2 vowels out of 4 = 4C2

Number of ways of selecting 3 consonants out of 7 and 2

vowels out of 4 = 7C3 x 4C2

=(7×6×5/3×2×1)×(4×3/2×1)=210

It means that we can have 210 groups where each group

contains total 5 letters(3 consonants and 2 vowels).

Number of ways of arranging 5 letters among themselves = 5! = 5 x 4 x 3 x 2 x 1 = 120

Hence, Required number of ways = 210 x 120 = 25200

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Q539.
In how many different ways can the letters of the word 'MATHEMATICS' be arranged so that the vowels always come together ?
1) 100800 2) 120960
3) 240150 4) 4989600
5)None of thesae
Answer : 120960
Explanation :
In the word 'MATHEMATICS', we treat the vowels AEAI as one letter.
Thus, we have MTHMTCS (AEAI).
Now, we have to arrange 8 letters, out of which M occurs twice, T occurs twice and the rest are different.
Number of ways of arranging these letters = 8! / (2!)(2!)= 10080.
Now, AEAI has 4 letters in which A occurs 2 times and the rest are different.
Number of ways of arranging these letters = 4! /2! = 12.
So, required number of words = (10080 x 12) = 120960.

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Q540.
In how many ways can a group of 5 men and 2 women be made out of a total of 7 men and 3 women ?
1) 42 2) 48
3) 63 4) 90
5)None of these
Answer : 63
Explanation : The required number of ways = (7C5 x 3C2) = (7C2 x 3C1) = (7 x 6 )/(2 x 1) x 3 =  63.
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