The whole numbers 1 through 30 were each written on separate pieces of paper. Those 30 pieces of paper were put into a jar. One piece of paper will be randomly drawn from this jar. What is the probability that this piece of paper will have a prime number written on it?
Correct answer: D
Explanation
A. Incorrect. Remember that the probability of choosing a paper with a prime number on it is the total possible number of papers with prime numbers divided by the total number of papers in the jar. You may have divided the number of papers being chosen, 1, by the total number of papers in the jar, 30.
B. Incorrect. Remember that the probability of choosing a paper with a prime number on it is the total possible number of papers with prime numbers divided by the total number of papers in the jar. You may have divided the number of papers being chosen, 1, by the total number of papers in the jar without prime numbers on them, 20.
C. Incorrect. Remember that the probability of choosing a paper with a prime number on it is the total possible number of papers with prime numbers divided by the total number of papers in the jar. You may have divided the number of papers being chosen, 1, by the total number of papers in the jar with prime numbers on them, 10.
D. Correct. There are 10 prime numbers between 1 and 30: 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29. The probability of choosing a paper with a prime number on it is the total possible number of papers with prime numbers divided by the total number of papers in the jar, 10 over 30.
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