question: In what time a sum of money double itself at 7% per annum simple interest?
Options:
(A) 33 1/8%
(B) 33 1/3%
(C) 14 2/7%
(D) 32 1/3%
(E) 23 1/3%
answer: Stream of consciousness: P = (P*7*R)/100
R = 14 2/7% The answer is (C).
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question: The average age of a class of 32 students is 16 yrs. if the teacher's age is also included, the average increases by one year. Find the age of the teacher
Options:
(A) 49
(B) 88
(C) 25
(D) 18
(E) 11
answer: Stream of consciousness: Total age of students is 32X16 = 512 Years
Total age inclusive of teacher = 33X (16+1) = 561
So, Teacher's age is 561-512 = 49 Yrs The answer is (A).
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question: The average of seven numbers is 21. The average of first three numbers is 19 and the average of last three numbers is 23. What is the middle number?
Options:
(A) 20
(B) 22
(C) 18
(D) 19
(E) 21
answer: Stream of consciousness: The total of seven numbers = 7X21 = 147
The total of first 3 and last 3 numbers is = 3 X 19+3 X 23 = 126
So, the middle number is (147 - 126 ) = 21 The answer is (E).
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question: The average of seven numbers is 18. The average of first three numbers is 14 and the average of last three numbers is 23. What is the middle number?
Options:
(A) 25
(B) 27
(C) 15
(D) 32
(E) 34
answer:
Stream of consciousness: The total of seven numbers = 7X18 = 126
The total of first 3 and last 3 numbers is = 3 X 14+3 X 23 = 111
So, the middle number is (126 - 111 ) = 15 The answer is (C).
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