Cross products?

Question

kamisha is planning to conduct a survey at her school. she has decided to interview seven out of every 30 students. if there are 570 students at her school, how many students must she interview?

Answer 1

7/30 =x/570

30x = 3990

x = 3990/30 = 133.

Answer 2

7 out of every 30

 

currently total of 570 students so we must know how many batches of 30 students are in the 570. divide the total number of students by the 30

 

570/30=19

 

this is means I will have 19 batches of 30. 7 out of 30 students, will be 7 times this 19 batches...i.e. 7*19=133

 

simply written

 

7/30*570=133

 

she must interview 133 students