Question
If the average cost price of 20 identical pens decreases
by Rs. 2 after replacing one pen with a new pen that costs Rs. 80, what was the original cost price of the replaced pen?Solution
ATQ;
Let the cost price of each pen be Rs. 'x'
So, cost price of 20 pencils = Rs. 20x
ATQ;
(20x - x + 80) ÷ 20 = x - 2
Or, 19x + 80 = 20x - 40
Or, x = 120
So, cost price of the pen that was removed is Rs. 120.
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