Answers Normal distribution

Exercises

1. The mean of one entrance exam was 60 and the standard deviation was 12. The results followed the normal distribution.

a) What was the score required for selection if 50% of the candidate was selected.

b) What was the score required for selection if 30% of the candidate was selected.

c) How many scored more than 65 points in the tests

Answers: a) 60 b) 54 c) 34%

2. Simo-Elmeri was late for school every day. His time of delay followed the normal distribution. The mean was five minutes and the standard deviation was 2 minutes.

a) In what probability was Simo-Elmeri more than seven minutes late?

b) What is the probability that Simo-Elmeri was less than four minutes late?

c) In what probability was Simo-Elmeri more than four but less than seven minutes late

Answers: a) 16% b) 31% c) 53%

3. The dice are rolled 810 times. What is the probability of getting 410 to 420 even numbers?

Answer: About 24%

4. It is known that 85% of the 385 guests invited to the party will arrive. The party has 333 seats. In what probability are the seats sufficient?

Answer: This is a binomial experiment and the normal distribution approximation gives an answer of 81%