Data Sufficiency - Weight of a student after swapping

Question

The average weight of a class of 100 students is 45 kg. The class consists of two sections, I and II, each with 50 students. The average weight, $W_I$ , of Section I is smaller than the average weight $W_{II}$ , of Section II. If the heaviest student say Deepak, of section II is moved to Section I, and the lightest student, say Poonam, of Section I is moved to Section II, then the average weights of the two sections are switched, i.e., the average weight of Section I becomes $W_{II}$ and that of Section II becomes $W_I$ . What is the weight of Poonam?

A: $W_{II} - W_I = 1.0$ . B: Moving Deepak from Section II to I (without any move I to II) makes the average weights of the two sections equal.

Accepted Answer

C. Let Deepak's weight be $D$ and Poonam's weight be $P$. Using A: gives $W_{II} - W_I = 1.0$. Using B: allows us to express $D$ in terms of section averages. Combining both statements gives enough information to solve for $P$.

Answer

Question can be answered using A alone but not using B alone

Answer

Question can be answered using B alone but not using A alone

Answer

Question can be answered using A and B together, but not using either A or B alone

Answer

Question cannot be answered even using A and B together

Data Sufficiency - Weight of a student after swapping

Explanation

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