Which of the following is equal to the average (arithmetic mean) of (x+5)^2 and (x-5)^2?
Options:
(A) x^2
(B) x^2+2
(C) x^2 +30
(D) x^2+20
(E) x^2+25
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Avg = [(x+5)^2 + (x-5)^2] / 2
Expanding and simplifying, (x^2 + 10x + 25 + x^2 - 10x + 25) / 2 = x^2 + 25 So the answer is: (E).
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In what time will a railway train 40 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
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T = 40/36 * 18/5 = 4 sec So the answer is: (B).
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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
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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 So the answer is: (A).
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