Blood Types:
45% O type
40% A type
4% AB type
11% B type
a) In a survey, 126 people had type O blood.
Predict how many people were surveyed.
Hint: use a proportion to solve for the unknown.

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?