We can use the z-score to find the probability of many other events. Let's explore those now. a. Suppose that the mean time a typical American teenager spends doing homework each week is 4.2 hours. Assume the standard deviation is
0.9 hour. Assuming the variable is normally distributed, find the percentage of American teenagers who spend less than 3.5 hours doing
homework each week.
b. According to a College Board report, the population of American 2008 high school graduates had a mean Math SAT score of 515 with
standard deviation of 116. What is the probability that of a randomly selected senior from this population scoring between 500 and 800 on the
Math portion of the SAT Reasoning Test?

which expression represents the approximate length of bc?

step-by-step explanation:

the correct option is 2.

step-by-step explanation:

according to the given information triangle abc is a right angle triangle with right angle at a. segment ab is 5 and segment ac is 7. point d is on segment bc and angles adb and adc are right angles.

it is given that triangles abd, cad, and cba are similar.

two triangles are similar if their corresponding sides are proportional.

in triangle cba, using pythagoras theorem

                      )

triangle abd and cba are similar,

                            (2)

triangle cad and cba are similar,

                      )

using (1), (2) and (3), we get

hence proved.

therefore option 2 is correct.