The compressive strength (in MPa) for a certain type of concrete has mean 22 and standard deviation 1.8. A random sample of 80 concrete cylinder is drawn. (i). What is the probability that the sample mean breaking strength is less than 20 MPa? (ii). How large a sample size is needed so that the probability of the sample mean being less than 22 MPa will be 0.01?
The compressive strength (in MPa) for a certain type of concrete has mean 22 and standard deviation 1.8. A random sample of 80 concrete cylinder is drawn. (i). What is the probability that the sample mean breaking strength is less than 20 MPa? (ii). How large a sample size is needed so that the probability of the sample mean being less than 22 MPa will be 0.01?
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![The compressive strength (in MPa) for a certain type of concrete has mean 22 and
standard deviation 1.8. A random sample of 80 concrete cylinder is drawn.
(i). What is the probability that the sample mean breaking strength is less than 20
MPa?
(ii). How large a sample size is needed so that the probability of the sample mean
being less than 22 MPa will be 0.01?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F12648a3c-57f4-45d3-9877-1e5e652eee58%2F44621f17-7386-41f4-b234-54d2fcd7e36e%2Fl4fnnn4_processed.png&w=3840&q=75)
Transcribed Image Text:The compressive strength (in MPa) for a certain type of concrete has mean 22 and
standard deviation 1.8. A random sample of 80 concrete cylinder is drawn.
(i). What is the probability that the sample mean breaking strength is less than 20
MPa?
(ii). How large a sample size is needed so that the probability of the sample mean
being less than 22 MPa will be 0.01?
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