Chair P, from Design Solutions, cost $60 per chair. Chair Q, from Seat

Question

Chair P, from Design Solutions, cost $60 per chair. Chair Q, from Seat Unlimited, costs $90 per chair. An office manager often has to buy several chairs to stock the floor space of new offices. On one occasion, she orders p of chair P, and q of chair Q. The average cost of a chair would be

average =  \frac{60p + 90q}{p + q}

In the table, select a value for p and a value for q corresponding to an average cost per chair of $70. Make only two selections, one in each column.

charlie1195 · Answer

This is a weighted average question.

We know that (60p + 90q)/(p+q) = 70
Solving it further, we get 
60p + 90q = 70p + 70q
20q = 10p
2q = p

Now, as per the options, there's just one pair of p and q that satisfies this condition, i.e., q=28 and p=56.

Bismuth83 · Answer

1. The formula and the value for the average can be put together:

70 = \frac{60p + 90q}{p + q}

2. Since there is no other information given, we can simplify the expression.

70 = \frac{60p + 90q}{p + q} \rightarrow 70p + 70q = 60p + 90q \rightarrow 10p = 20q \rightarrow p = 2q

3. The only two answers that match a ratio of 1:2 are 28 and 56.

4. So, our answer will be:   p - 28 and q - 56  .

p	q	Number of chairs
		21
		28
		36
		45
		56
		63

Chair P, from Design Solutions, cost $60 per chair. Chair Q, from Seat

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GMAT Two-part Analysis (TPA) Questions

Chair P, from Design Solutions, cost $60 per chair. Chair Q, from Seat

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