Question

(a) The distribution of IQ scores for high school graduates is normally distributed with mean 400 and standard deviation 80. (i) What is the 90th percentile of this distribution of the IQ scores? (3 marks) (ii) Find the IQ scores that form the boundaries of the middle 60% of the distribution of the scores. (4 marks) (iii) What is the probability that a randomly selected score exceeds 375? (3 marks) (Round your answer to 4 decimal places) (b) An airline finds that 5% of the persons making reservations on a certain flight will not show up for the flight. If the airline sells 160 tickets for a flight that has only 155 seats, what is the probability that a seat will be available for every person holding a reservation and planning to fly? (5 marks) 

          (a) The distribution of IQ scores for high school graduates is normally distributed with mean 400 and standard deviation 80.
(i) What is the 90th percentile of this distribution of the IQ scores? (3 marks)
(ii) Find the IQ scores that form the boundaries of the middle 60% of the distribution of the scores. (4 marks)
(iii) What is the probability that a randomly selected score exceeds 375? (3 marks) (Round your answer to 4 decimal places)
(b) An airline finds that 5% of the persons making reservations on a certain flight will not show up for the flight. If the airline sells 160 tickets for a flight that has only 155 seats, what is the probability that a seat will be available for every person holding a reservation and planning to fly? (5 marks)
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(a) The distribution of IQ scores for high school graduates is normally distributed with mean 400 and standard deviation 80. (i) What is the 90th percentile of this distribution of the IQ scores? (3 marks) (ii) Find the IQ scores that form the boundaries of the middle 60% of the distribution of the scores. (4 marks) (iii) What is the probability that a randomly selected score exceeds 375? (3 marks) (Round your answer to 4 decimal places) (b) An airline finds that 5% of the persons making reservations on a certain flight will not show up for the flight. If the airline sells 160 tickets for a flight that has only 155 seats, what is the probability that a seat will be available for every person holding a reservation and planning to fly? (5 marks)

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Elementary Statistics a Step by Step Approach
Elementary Statistics a Step by Step Approach
Allan G. Bluman 9th Edition
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Question # 2 (Total marks: 15) (a) The distribution of IQ scores for high school graduates is normally distributed with mean 400 and standard deviation 80. (i)| What is the 90th percentile of this distribution of the IQ scores? (3 marks) (ii) Find the IQ scores that form the boundaries of the middle 60% of the distribution of the scores. (4 marks) (iii) What is the probability that a randomly selected score exceeds 375? 3 marks) (Round your answer to 4 decimal places) (b) An airline finds that 5% of the persons making reservations on a certain flight will not show up for the flight. If the airline sells 160 tickets for a flight that has only 155 seats, what is the probability that a seat will be available for every person holding a reservation and planning to fly? (5 marks)
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The distribution of IQ scores for high school graduates is normally distributed with mean 400 and standard deviation 80. (i) What is the 90th percentile of this distribution of the IQ scores? (ii) Find the IQ scores that form the boundaries of the middle 60% of the distribution of the scores. (iii) What is the probability that a randomly selected score exceeds 375? (Round your answer to 4 decimal places)

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Transcript

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00:01 Here the mean mu is given as 400 and standard deviation sigma is 80.
00:09 So the first question is we need to find the 90th percent of this distribution of iq score.
00:26 Therefore, p of z equal to 90 percentage which is 0 .9.
00:35 And z score corresponding to this is 1 .2815.
00:39 Now substitute here and find the value of x.
00:42 So z equal to x minus mu by sigma, which implies 1 .281 .2...
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