Question

5 balls pens costing Rs.350 each and 10 gel pens costing Rs.50 each. Find the average cost.
1. Rs 150
2. Rs 200
3. Rs 130
4. Rs.170

Answer 1

Correct Answer - Option 1 : Rs 150

Given

cost of 5 balls pens = Rs.350 each

cost pf 10 gel pens = Rs.50 each

Formula used

When two groups and its average is given, then formula is used as follows.

Average = (N1a1 + N2a2)/N1 + N2

Where N1 , N2, a1 and a2 are number of observation in a group and  average of two group

Calculation

Average = [5(350) + 10(50)]/(5 + 10)

⇒(1750 + 500)/15

⇒2250/15

⇒150

∴ Average cost of 15 pens is Rs 150