If y is directly proportional to x and y = 17.5 when x=21 find y when x=39

direct proportion y=kx , k is constant and k does not equal to 0.

17.5=k(21)

k=5/6

when x =39

y=5/6 ×39

y=32.5

21 = 39

—. —

17.5 Y

21y= 682.5

Y=32.5

ANOTHER WAY TO SOLVE IT IS...

Y=kx

17.5=k*21

.833=k

S

Y=kx

Y=.833*39

Y=32.5

b. 153 students do not participate in sports and seventy-five 12th graders were surveyed