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NARA [144]
3 years ago
13

Certain tubes manufactured by a company have a mean lifetime of 800 hours and a standard deviation of 60 hours. Find the probabi

lity that a random sample of 16 tubes taken from the group will have a mean lifetime (a) between 790 and 810 hours, (b) less than 785 hours, (c) more than 820 hours, (d) between 770 and 830 hours
Mathematics
1 answer:
Anna71 [15]3 years ago
4 0

Answer:

Step-by-step explanation:

given that certain tubes manufactured by a company have a mean lifetime of 800 hours and a standard deviation of 60 hours.

Sample size n =16

Std error of sample mean = \frac{\sigma}{\sqrt{n} } \\= 15

x bar follows N(800, 15)

the probability that a random sample of 16 tubes taken from the group will have a mean lifetime

(a) between 790 and 810 hours,

=P(790

(b) less than 785 hours

=P(X

, (c) more than 820 hours,

=P(X>820)\\=p(Z>1.333)\\= 0.0913

(d) between 770 and 830 hours

=P(|Z|

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