7 part b )
The reading speed of second grade students in a large city is
approximately normal, with a mean of
91
words per minute (wpm) and a standard deviation of 10 wpm.
Complete parts (a) through (f).
(a) What is the probability a randomly selected student in the
city will read more than
96
words per minute?The probability is
. 3085.3085.
(Round to four decimal places as needed.)
Interpret this probability. Select the correct choice below and
fill in the answer box within your choice.
A.If 100 different students were chosen from
this population, we would expect
nothing
to read exactly
96
words per minute.
B.If 100 different students were chosen from
this population, we would expect
nothing
to read more than
96
words per minute.
C.If 100 different students were chosen from
this population, we would expect
nothing
to read less than
96
words per minute.
8 part b )
Suppose a geyser has a mean time between eruptions of
80 minutes.
Let the interval of time between the eruptions be normally
distributed with standard deviation 21 minutes.
Complete parts (a) through (e) below.
(a) What is the probability that a randomly selected time
interval between eruptions is longer than 89
minutes?
The probability that a randomly selected time interval is longer
than 89 minutes is approximately . 3336
(Round to four decimal places as needed.)
(b) What is the probability that a random sample of 10 time
intervals between eruptions has a mean longer than 89
minutes?
The probability that the mean of a random sample of 10 time
intervals is more than 89 minutes is approximately
(Round to four decimal places as needed.)