Question

If y is direct proportional to 1/x and x=2 when y=20 what is the value of x when y=1.25

Answer 1

Y is directly proportional to 1/x

xy=k (where k is constant)

so,

for x=2 and y=20

k=xy

k=2×20

k=40-(1)

now,

for y=1.25

k=xy

k=x×1.25

k=1.25x-(2)

from equation (1) & (2)

40=1.25x

40/1.25=x

x=32