Lee Iacocca volunteered to drive one of his Chryslers into a brick wall to demonstrate the effectiveness of airbags used in these cars. Airbags are known to acti- vate at random when the car decelerates anywhere from 9 to 14 miles per hour per second (mph/s). The probability distribution for the deceleration speed at which bags activate is given below.
|
mph/s
|
Probability
|
|
9
|
0.12
|
|
10
|
0.23
|
|
11
|
0.34
|
|
12
|
0.21
|
|
13
|
0.06
|
|
14
|
0.04
|
a. If the airbag activates at a deceleration of 12 mph/s or more, Iacocca would get hurt. What is the probability of his being hurt in this demon- stration?
b. What is the mean deceleration at airbag activation moment?
c. What is the standard deviation of deceleration at airbag activation time?