average Model Questions & Answers, Practice Test for ibps clerk prelims

Answer: (a)

Average weight of T,P and R is 54.33333 kg or 163/3 kg

So total weight of T,P and R is

(163/3)×3=163kg

Now average weight of T,F and G is 53kgs

So total of these three=53×3=159kgs

As T's weight is included in both groups

It had to be removed from one of the group

159 – (54 1/3) = 104.666667 kgs or 314/3 kgs (F and G)

Total weight of P,T,R,Fand G is

163 + 314 / 3 = 267.666667 kgs or (803/3) kgs

Average of these 5,

267.666667 / 5 = 53.33333 kgs

Or

(803 / 3 × 5) = 803 / 15 = 53.333333 kgs.

Answer: (b)

A + B + C = 3 × 84 = 252 kg

A + B + C + D = 4 × 80 = 320 kg

∴ D = 320 – 252 = 68 kg

∴ E = 68 + 3 = 71 kg

Now, ${320 - A + 71}/4 = 79$

∴ A = 75 kg

Answer: (d)

Sum of 'm' numbers = m.$n^4$

Sum of 'n' numbers = n.$m^4$

Sum of 'm + n' numbers = $mn^4 + nm^4$

Average of 'm + n' numbers

= ${mn^4 + nm^4}/(m + n)$

= ${mn(n^3 + m^3)}/(m + n)$

= ${mn(m + n)(m^2 + n^2 - mn)}/(m + n)$

= $mn(m^2 + n^2 – mn)$

So, option (d) is correct.

Answer: (b)

6 × 49 + 6 × 52 – 11 × 50

= 294 + 312– 550 = 56

Answer: (c)

Sum of 10 numbers = 402

Corrected sum of 10 numbers

= 402 – 13 + 31 – 18 = 402

Hence, correct average = $402/10$ = 40.2