Chapter 7, Problem AP2.4CPT

To determine

To find: a proper way to use a table of random digits to do this.

Answer to Problem AP2.4CPT

One digit from the random digit table simulates one answer, with 0 or 1= correct and all other digits = incorrect. Ten digits from the table simulate 10 answers.

Explanation of Solution

1. Incorrect, because 5 of the 10 possible digits associated with a true answer, which associated with a probability of $5/10=1/2$ instead of $1/5$ .
2. Correct, because 2 of the 10 possible digits associated with a true answer, which associated with a probability of $2/10=1/5$ instead of $1/5$ .
3. Incorrect, because 5 of the 10 possible digits associated with a true answer, which associated with a probability of $5/10=1/2$ instead of $1/5$ .
4. Incorrect, because repeats are being ignored and therefore the probability of obtaining a correct answer is then not the same for each question (while this probability should be constant).
5. Incorrect, because 21 of the 100 possible pairs of digit associated with a true answer, which associated with a probability of $21/100$ instead of $1/5=21/100$ .

Hence, the correct option is (b)