How many visitors bought both products

Question

Hi,

In a shop, 30 visitors visited, out of them 16 bought pen, 12 bought phone and 10 bought nothing.

What percentage visitors bought both pen and phone ? May I know please how to solve this problem ?

Answer 1

Total visitors = 30

10 bought nothing so only 20 actually bought something (pen, phone, or both)

 

Let Visitors who bought both pen and phone = x

 

Visitors who bought only pen = 16-x

 

Visitors who bought only phone = 12-x

 

These 3 must sum to 20:

x + (16-x) + (12-x) = 20

28 - x = 20

-x = -8

x = 8 that bought both pen and phone

 

So your question is:  8 is what percentage of 30?

8 = (x/100)30

 

x = 800/30 = 80/3 = 26 2/3 % or 26.67%