A trader earned Rs. 500 by selling at Rs. 5 per unit, Rs. 500 by selling at Rs. 10 per unit and Rs. 500 by selling at Rs. 20 per unit. What was his average price per unit (rounded to 2 decimals)?
Solution
As the revenues are equal here, the average price per unit is the harmonic mean of individual price per units.
Average Price per unit
=51+101+2013=204+2+13=760=8.57
Note: The revenue of Rs. 500 does not matter while calculating the average. Only the fact that the revenues earned were equal matters.
Alternatively
When in doubt you can always apply the general average principle.
Average Price per unit =Total units soldTotal Revenue
Number of Units sold =5500+10500+20500=100+50+25=175
Average Price per unit =175500+500+500=760=8.57
Answer: 8.57