The time it takes to travel from home to the office is normally distributed with minutes and minutes.
a. What is the probability the trip takes more than 20 minutes?
On your TI-83 or TI-84 calculator:
1. Press CLEAR
2. Press 2ND
3. Press VARS
4. Press 2
6. You see normalcdf(
7. After that type in: 20,999999999,25,5) so that what you see
is this
normalcdf(20,999
999999,25,5)
8. Press ENTER
9. Read the answer .8413447404
b. What is the probability the trip takes less than 15 minutes.
1. Press CLEAR
2. Press 2ND
3. Press VARS
4. Press 2
6. You see normalcdf(
7. After that type in: -999999999,15,25,5) so that what you see
is this:
normalcdf(-99999
9999,15,25,5)
Caution: be sure that the "-" is the NEGATIVE sign on the
very bottom right button, that looks liks this (-), and NOT
the minus sign above the + button.
8. Press ENTER
9. Read the answer .022750062
c. What is the probability the trip takes between 30 and 35 minutes?
1. Press CLEAR
2. Press 2ND
3. Press VARS
4. Press 2
6. You see normalcdf(
7. After that type in: 30,35,25,5) so that what you see
is this
normalcdf(30,35,
25,5)
8. Press ENTER
9. Read the answer .1359051975
d. What is the probability the trip takes more than 40 minutes?
1. Press CLEAR
2. Press 2ND
3. Press VARS
4. Press 2
6. You see normalcdf(
7. After that type in: 40,999999999,25,5) so that
what you see is this
normalcdf(40,999
999999,25,5)
8. Press ENTER
9. Read the answer .0013499672
If you're supposed to use tables and not a calculator, then
post again telling us whether you have the kind of tables
with both negative and positive z-scores or whether you have
the kind with onl;y positive z-scores.
Edwin