Multiple choice

I went to a hotel along with 12 friends. I paid Rs145 and all the others paid an equal amount. In the end, we did some calculations and found that the average sum paid by all of us was Rs5 more than what was originally paid by each of my friends. How much money did each of my friends pay?

  1. 120

  2. 100

  3. 80

  4. 70

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let x be the amount each friend paid. Total amount = 145 + 12x. Average = (145+12x)/13 = x+5. Solving: 145+12x = 13x+65, so 145-65 = 13x-12x, therefore 80 = x. Each friend paid Rs80. This gives average = (145+960)/13 = 1105/13 = 85, which is indeed Rs5 more than Rs80.

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