A company produces rechargeable batteries for small size string trimmers. We define the life of the battery as the time between starting the string trimmer until the trimmer stops due to battery failure. It is known that the life of such batteries follows the normal distribution with mean 29.5 minutes and deviation of 1.52 minutes. 8. Find the probability that the life of a randomly selected battery is less than 28 minutes. A 0.1190 B 0.1335 C 0.1446 D 0.1611 E 0.1762 9. Find the probability that the life of a randomly selected battery is more than 30 minutes. A 0.3707 B 0.3483 C 0.3557 D 0.3632 E 0.3783 10. Find the probability that the life of a randomly selected battery is between 28 and 30 minutes. A 0.5327 B 0.5108 C 0.4923 D 0.4455 E 0.4682
Questions 8 - 10
A company produces rechargeable batteries for small size string trimmers. We define the life of the battery as the time between starting the string trimmer until the trimmer stops due to battery failure. It is known that the life of such batteries follows the
8.
Find the probability that the life of a randomly selected battery is less than 28 minutes.
A 0.1190
B 0.1335
C 0.1446
D 0.1611
E 0.1762
9.
Find the probability that the life of a randomly selected battery is more than 30 minutes.
A 0.3707
B 0.3483
C 0.3557
D 0.3632
E 0.3783
10.
Find the probability that the life of a randomly selected battery is between 28 and 30 minutes.
A 0.5327
B 0.5108
C 0.4923
D 0.4455
E 0.4682
Questions 11 - 13
Mark is a mechanic who is specialized in performing service on Honda cars. His clients have to make an appointment at least one week ahead but sometimes there are last minute cancellations. All of Mark’s income comes from these services and he works from Monday to Friday. Let R be the number of cars on which Mark performs service in a randomly selected day. The probability distribution of the random
variable R is given in the probability table below.
| r | P(r) |
| 3 | 0.07 |
| 4 | 0.12 |
| 5 | 0.17 |
| 6 | 0.24 |
| 7 | 0.18 |
| 8 | 0.13 |
| 9 | 0.09 |
Find the probability that Mark performs service on less than 6 cars in a randomly selected day.
A 0.45
B 0.44
C 0.40
D 0.33
E 0.36
12.
Find the probability that Mark performs service on more than 6 cars in a randomly selected day.
A 0.36
B 0.38
C 0.40
D 0.44
E 0.41
13.
Find the expected number of cars on which Mark performs service in a randomly selected week.
A 6.09
B 5.83
C 5.88
D 5.99
E 6.15
Step by step
Solved in 3 steps with 2 images
