60 of 42 out of 320

Question

Megan surveyed a random sample of 60 students at her school and found that 42 of them ride the bus to school each day. If there are 320 students at Megan's school, about how many of them ride the bus to school each day?

Answer 1

Set up a ratio 

 

42 is to 60 as X is to 320 

 

42:60 :: X:320 

 

In fraction form this is 

 

42/60 = X/320  

 

Cross multiply to get 

 

60*X = 42*320

X = (42*320) / 60 = (42*32) / 6 = 7*32 = 224 

 

Check:  42/60 = 70% of sample ride the bus

            224/320 = 70% of students ride the bus