Multiple choice

The average weight of P, Q and R is 71 kg. If the average weight of P and Q is 66 kg and that of Q and R be 76.5 kg, then the weight (in kg) of Q is

  1. 60

  2. 72

  3. 81

  4. 75
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sum of P+Q+R = 71 * 3 = 213. Sum of P+Q = 66 * 2 = 132. Sum of Q+R = 76.5 * 2 = 153. Adding the last two gives P + 2Q + R = 285. Subtracting the first sum (P+Q+R=213) from this gives Q = 285 - 213 = 72.

AI explanation

The total weight of P, Q, and R is 71 multiplied by 3, which equals 213. The total weight of P and Q is 66 multiplied by 2, equaling 132, and the total weight of Q and R is 76.5 multiplied by 2, equaling 153. Adding the weights of (P plus Q) and (Q plus R) gives 132 plus 153, which equals 285. Subtracting the combined weight of all three (P plus Q plus R equals 213) from this sum isolates the weight of Q: 285 minus 213 equals 72.

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