ACT Math · Probability and counting

The probability of rain tomorrow is 0.35. What is the probability that it does NOT rain?

The probability of rain tomorrow is 0.35. What is the probability that it does NOT rain?

Answer and explanation

Answer: H: 0.65

The complement rule says P(not A)=1−P(A)P(\text{not }A)=1-P(A). Here 1−0.35=0.651-0.35=0.65, choice H. The probabilities of rain and no rain must add to 11, and 0.35+0.65=10.35+0.65=1. Choice F (0.350.35) is the probability of rain itself. Choice J (1.351.35) adds instead of subtracting, which gives an impossible probability greater than 11. Choice G (0.550.55) comes from a subtraction slip. A probability is always between 00 and 11, so choice J can be eliminated without calculation.

More Probability and counting questions

All Probability and counting questions

Learn the method behind questions like this one

The ACT Math course teaches each tested skill through lessons, step-by-step solutions to sample problems, the complete study guide and full-length practice tests.