# Very Imp. Aptitude Questions for Freshers : Learn 5 Q's daily

1) A is two years older than B who is twice as old as C. If the total of the ages of A, B and C be 27, the how old is B?

a)7     b)4    c)9    d)10

Explanation :

Assume C's age be x years. Then, B's age = 2x years. A's age = (2x + 2) years.

Sum of ages = 27

(2x + 2) + 2x + x = 27

5x = 25

x = 5.

Finally, B's age = 2x = 10 years.

2) Which one of the following is not a prime number?

A. 31         B. 61
C. 71         D. 91

Explanation:

91 is divisible by 7. So, it is not a prime number.

prime number : an integer that has no integral factors but itself and 1

3) Some Basic Formula:
1. (a + b)(a - b) = (a2 - b2)

2. (a + b)2 = (a2 + b2 + 2ab)

3. (a - b)2 = (a2 + b2 - 2ab)

4. (a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca)

5. (a3 + b3) = (a + b)(a2 - ab + b2)

6. (a3 - b3) = (a - b)(a2 + ab + b2)

7. (a3 + b3 + c3 - 3abc) = (a + b + c)(a2 + b2 + c2 - ab - bc - ac)

4) Three unbiased coins are tossed. What is the probability of getting at most two heads?

A.34            C.38
B.14            D.78

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}.

P(E) = n(E)/n(S) = 7/8.

5) The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:

A. 27 kg B. 21 kg
C. 36 kg D. 31 kg

Explanation:

Let A, B, C represent their respective weights. Then, we have:

A + B + C = (45 x 3) = 135 .... (i)

A + B = (40 x 2) = 80 .... (ii)

B + C = (43 x 2) = 86 ....(iii)

Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)

Subtracting (i) from (iv), we get : B = 31.

B's weight = 31 kg.