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Maths for bank exams

In a group of persons, 70% of the persons are male and 30% of the persons are married. If two sevenths of males are married, what fraction of the females is single?

1. 2/7
2. 3/7
3. 2/3
4. 1/3

Answer

In a group, 70% are Males. So females = 30%

Now, two-seventh of males are married.

Married males = 2/7 * 70% = 20%

Total married persons = 30%

Married females = Total married - Married males = 30% - 20% = 10%

Total females = 30%

Out of every 3 females, one is married and two are unmarried.

The correct option is C.

A sum of Rs.700 has to be used to give seven cash prizes to the students of a school for their overall academic performance. If each prize is Rs.20 less than its preceding prize, what is the least value of the prize?

1. Rs. 30
2. Rs. 40
3. Rs. 60
4. Rs. 80

Answer

Let the least value price be X. Then the next value is X+20, and the next value is X+40 and on and on up to 7 values. So, seven cash prizes follow arithmetic progression with

First term = a (Least prize)

Common difference, d = 20

Number of terms, n = 7

Sum of AP = n/2 [2a + (n-1)d]

Sum = 700 = 7/2 [2*a+(7-1)*20]

700 = 7a + 420

a = 40

The correct option is B.

There are 100 students in a particular class. 60% students play cricket, 30% student play football and 10% student play both the games. What is the number of students who play neither cricket nor football?

1. 25
2. 20
3. 18
4. 15

Answer

Let Set A be the students playing cricket and Set B the students playing football.

Out of 100 students, 60% play cricket and 30% play football.

Set A (Cricket) = 60

Set B (Football) = 30

10% students play both cricket and football.

A ∩ B = 10

A ∪ B = A + B - (A ∩ B)

A ∪ B = 60 + 30 - 10 = 80

(A ∪ B)' = 100 - 80 = 20

The correct option is B.