q: A class consists of 100 students, 25 of them are girls and 75 boys; 20 of them are rich and remaining poor; 10 of them are fair complexioned. The probability of selecting a fair complexioned rich girl is
Options:
(A) 1/200
(B) 1/59
(C) 1/56
(D) 1/54
(E) 1/53
a: OK... The probability of selecting girl is: 25/100 = 1/4
The probability of selecting rich is: 20/100 = 1/5
The probability of selecting fair complexioned is: 10/100 = 1/10
Three are independent;probability of rich and fair complexioned girl is:
(1/4) (1/5) (1/10) = 1/200
The answer is (A).

q: The average mark obtained by 22 candidates in an examination is 47. The average of the first ten is 55 while the last eleven is 40 .The marks obtained by the 11th candidate is ?
Options:
(A) 22
(B) 44
(C) 49
(D) 68
(E) 76
a: OK... It is clear that 22 x 47 = 10 x 55 + K + 11 x 40 K = 44
The answer is (B).

q: Look at this series: 1.25, 7.5, ____, 270, 1620, ... What number should fill the blank?
Options:
(A) 50
(B) 65
(C) 45
(D) 55
(E) 40
a:
OK... This is a simple multiplication series. Each number is 6 times greater than the previous number.
The answer is (C).