Number of students out of surveyed students who live within 500 miles
= Total number of students surveyed - Number of students who live 500 miles away or more
= 750 - 120
= 630
Ratio of number of students surveyed to the number of students out of them living within 500 miles
= 750:630
= 25:21
Let the actual number of students living within 500 miles be x.
If the students are surveyed randomly then,
Ratio of number of students surveyed to the number of students out of them living within 500 miles = Ratio of actual number of students to the number of actual students living within 500 miles
=> 25:21 = 24000:x
=> 25/21 = 24000/x
=> x = (24000×21)/25
=> x = 504000/25
=> x = 20160
So, the number of actual students who live within 500 miles is 20160.
