Question

In: Statistics and Probability

For a certain standardized placement test, it was found that the scores were normally distributed, with...

For a certain standardized placement test, it was found that the scores were normally distributed, with a mean of 190 and a standard deviation of 30. Suppose that this test is given to 1000 students. (Recall that 34% of z-scores lie between 0 and 1, 13.5% lie between 1 and 2, and 2.5% are greater than 2.)

(a) How many are expected to make scores between 160 and 220?

(b) How many are expected to score above 250?

(c) What is the expected range of all the scores?

Solutions

Expert Solution


Related Solutions

In a recent​ year, the total scores for a certain standardized test were normally​ distributed, with...
In a recent​ year, the total scores for a certain standardized test were normally​ distributed, with a mean of 500 and a standard deviation of 10.5. Answer parts ​(a)dash​(d) below. ​(a) Find the probability that a randomly selected medical student who took the test had a total score that was less than 489. The probability that a randomly selected medical student who took the test had a total score that was less than 489 is . 1474. ​(Round to four...
In recent years, the total scores for a certain standardized test were normally distributed, with a...
In recent years, the total scores for a certain standardized test were normally distributed, with a mean of 500 and a standard deviation of 10.3 Answer parts A-D below. Round to four decimal places as needed. Find the probability that a randomly selected medical student who took the test has a total score that was less than 493. The probability that randomly selected medical student who took the test had a total score that was less than 493 is [____]...
The scores on a standardized test are normally distributed with a mean of 95 and standard...
The scores on a standardized test are normally distributed with a mean of 95 and standard deviation of 20. What test score is 0.5 standard deviations above the mean?
Scores of a standardized test are approximately normally distributed with a mean of 85 and a...
Scores of a standardized test are approximately normally distributed with a mean of 85 and a standard deviation of 5.5. (a) What proportion of the scores is above 90? (b) What is the 25th percentile of the scores? (c) If a score is 94, what percentile is it on?
Suppose that the scores on a statewide standardized test are normally distributed with a mean of...
Suppose that the scores on a statewide standardized test are normally distributed with a mean of 75 and a standard deviation of 2. Estimate the percentage of scores that were (a) between 73 and 77. % (b) above 79. % (c) below 73. % (d) between 69 and 79. %
Scores for a common standardized college aptitude test are normally distributed with a mean of 481...
Scores for a common standardized college aptitude test are normally distributed with a mean of 481 and a standard deviation of 108. Randomly selected men are given a Test Prepartion Course before taking this test. Assume, for sake of argument, that the test has no effect. If 1 of the men is randomly selected, find the probability that his score is at least 537.1. P(X > 537.1) = Enter your answer as a number accurate to 4 decimal places. NOTE:...
Scores for a common standardized college aptitude test are normally distributed with a mean of 512...
Scores for a common standardized college aptitude test are normally distributed with a mean of 512 and a standard deviation of 111. Randomly selected men are given a Test Prepartion Course before taking this test. Assume, for sake of argument, that the test has no effect. If 1 of the men is randomly selected, find the probability that his score is at least 591.7. P(X > 591.7) = Enter your answer as a number accurate to 4 decimal places. If...
Scores for a common standardized college aptitude test are normally distributed with a mean of 514...
Scores for a common standardized college aptitude test are normally distributed with a mean of 514 and a standard deviation of 97. Randomly selected men are given a Test Prepartion Course before taking this test. Assume, for sake of argument, that the test has no effect. If 1 of the men is randomly selected, find the probability that his score is at least 555.2. P(X > 555.2) = Enter your answer as a number accurate to 4 decimal places. NOTE:...
Scores for a common standardized college aptitude test are normally distributed with a mean of 496...
Scores for a common standardized college aptitude test are normally distributed with a mean of 496 and a standard deviation of 101. Randomly selected men are given a Test Prepartion Course before taking this test. Assume, for sake of argument, that the test has no effect. If 1 of the men is randomly selected, find the probability that his score is at least 547.1. P(X > 547.1) = (Enter your answer as a number accurate to 4 decimal places) If...
A standardized​ exam's scores are normally distributed. In a recent​ year, the mean test score was...
A standardized​ exam's scores are normally distributed. In a recent​ year, the mean test score was 21.4 and the standard deviation was 5.4. The test scores of four students selected at random are 15​, 22​, 9​, and 36. Find the​ z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 15 is:
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT