Jon finds a box of 350 postcards. He selects a random sample of 75 postcards and finds that 27 already have a stamp on them. Predict the total number of postcards in the box with stamps on them.

126

Step-by-step explanation:

Let the total number of postcard with stamp on it = x

Out of 350 postcards, x has stamp on it.

Out of 75 postcards, 27 has stamp on it.

Expressing these as a ratio:

350:x=75:27

350/x=75/27

Cross multiply

75x=350*27

x = (350*27) / 75

x = 126

Therefore, the the total number of postcards in the box with stamps on them is 126.