Question

Ian owns a small business selling used books. He knows that in the last week 19

customers paid cash, 30 customers used a debit card, and 77 customers used a credit
card.
If next week, he is expecting 1800 customers, about how many would you expect to
pay with a credit card? Round your answer to the nearest whole number.

Answer 1

Explanation:

last week there were 19+30+77 = 126 customers.

19/126 = 1/14 paid cash.

30/126 = 5/21 paid by debit card.

77/126 = 11/18 paid by credit card.

next week he expects 1800 customers.

that is compared to 126 a factor of

1800/126 = 300/21 = 100/7

now we actually only need to apply the same factor to any part of the total sum to get their share in the new total sum.

it simply follows the rule

(a + b + c) × d = ad + bd + cd

so,

77 × 100/7 = 11 × 100 = 1100 customers are expected to pay per credit card.