00:01
All right, so the question here is that in a recent year, the scores for the reading portion of a test were normally distributed with the mean of 20 .9 and standard deviation of 6 .2.
00:13
So here first part is to determine the probability that a randomly selected high school student who took the reading portion of the test has a score less than 17.
00:22
So this is equal to this will be equal to probability of x minus mean upon standard deviation less than 17.
00:31
Minus 20 .9 upon 6 .2, which is equal to probability of z less than minus 0 .62903, and this is equal to 0 .2647.
00:46
Right.
00:47
Now, the next part of this question, it says that what is the probability here that the score is in between 16 .4 and 25 .4.
00:58
Right so this is equal to probability of 16 .4 minus 20 .9 upon 6 .2 less than x minus mean upon standard deviation less than 25 .4 minus 20 .9 upon 6 .2.
01:15
So this is equal to probability minus 0 .7258 less than z less than 0 .7258.
01:29
So this is equal to probability of z less than 0 .7258 minus probability of z less than minus 0 .7258...