An IQ test consists of 80 multiple choice questions. A question is selected at random. Find the probability that the question number is divisible by both 2 and 5
To find the probability that a question number is divisible by both 2 and 5, we need to find the numbers that are divisible by both 2 and 5 between 1 and 80.
These numbers are multiples of the least common multiple of 2 and 5, which is 10. So, we need to find the multiples of 10 between 1 and 80, which are 10, 20, 30, 40, 50, 60, 70, and 80.
There are a total of 8 numbers that are divisible by both 2 and 5 between 1 and 80.
Therefore, the probability of selecting a question number that is divisible by both 2 and 5 is:
Probability = Number of favorable outcomes / Total number of outcomes
Probability = 8 / 80
Probability = 1 / 10
So, the probability that a question number is divisible by both 2 and 5 is 1/10 or 0.1.