SaiBook.us Statistics

Lesson Example Discussion Quiz: Class Homework

Quiz In Class

Title: Normal distribution

Grade: 9-a Lesson: S4-L9

Explanation: Hello Students, time to practice and review. Let us take next 10-15 minutes to solve the five problems using the Quiz Sheet. Then submit the quiz to get the score. This is a good exercise to check your understanding of the concepts.

Quiz: in Class

Problem Id	Problem	Options
1	The length of life of an instrument produced by a machine has a normal ditribution with a mean of 12 months and standard deviation of 2 months. Find the probability that an instrument produced by this machine will last less than 7 months.	A) 0.0204 B) 0.0062 C) 0.1089 D) 0.2062
2	The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be assembled at this plant in a period of time between 20 and 22 hours?	A) 0.3413 B) 0.1554 C) 0.1589 D) 0.3485
3	A large group of students took a test in Physics and the final grades have a mean of 70 and a standard deviation of 10. If we can approximate the distribution of these grades by a normal distribution, what percent of the students scored higher than 80?	A) 21.45% B) 19.45% C) 15.87% D) 17.21%
4	The annual salaries of employees in a large company are approximately normally distributed with a mean of $50,000 and a standard deviation of $20,000.What percent of people earn less than $40,000?	A) 45.87% B) 15.14% C) 21.45% D) 30.85%
5	The chest diameter of 18 year od malefootballers is normally distributed with a mean of 95 cm and a standard deviation of 8 cm.Find the percentage of footballers with chest measurement between 103 cm and 111 cm.	A) 15.5% B) 21.5% C) 18.5% D) 13.5%

Problem Id

Problem

Options

The length of life of an instrument produced by a machine has a normal ditribution with a mean of 12 months and standard deviation of 2 months. Find the probability that an instrument produced by this machine will last less than 7 months.

A) 0.0204
B) 0.0062
C) 0.1089
D) 0.2062

The time taken to assemble a car in a certain plant is a random variable having a normal distribution of 20 hours and a standard deviation of 2 hours. What is the probability that a car can be assembled at this plant in a period of time between 20 and 22 hours?

A) 0.3413
B) 0.1554
C) 0.1589
D) 0.3485

A large group of students took a test in Physics and the final grades have a mean of 70 and a standard deviation of 10. If we can approximate the distribution of these grades by a normal distribution, what percent of the students scored higher than 80?

A) 21.45%
B) 19.45%
C) 15.87%
D) 17.21%

The annual salaries of employees in a large company are approximately normally distributed with a mean of $50,000 and a standard deviation of $20,000.What percent of people earn less than $40,000?

A) 45.87%
B) 15.14%
C) 21.45%
D) 30.85%

The chest diameter of 18 year od malefootballers is normally distributed with a mean of 95 cm and a standard deviation of 8 cm.Find the percentage of footballers with chest measurement between 103 cm and 111 cm.

A) 15.5%
B) 21.5%
C) 18.5%
D) 13.5%