Answer:
The percent of the parts are expected to fail before the 2100 hours is 0.15.
Step-by-step explanation:
Given :Life tests on a helicopter rotor bearing give a population mean value of 2500 hours and a population standard deviation of 135 hours.
To Find : If the specification requires that the bearing lasts at least 2100 hours, what percent of the parts are expected to fail before the 2100 hours?.
Solution:
We will use z score formula

Mean value = 
Standard deviation = 
We are supposed to find If the specification requires that the bearing lasts at least 2100 hours, what percent of the parts are expected to fail before the 2100 hours?
So we are supposed to find P(z<2100)
so, x = 2100
Substitute the values in the formula


Now to find P(z<2100) we will use z table
At z = −2.96 the value is 0.0015
So, In percent = 
Hence The percent of the parts are expected to fail before the 2100 hours is 0.15.
4th term would be
250 - (n-1)•13
250 - (4-1)•13
250 - 39
211
check:
250
237
224
211
I can't tell what the numbers are on the first one but you got the second one right, and the last one would be different it would be 24 I believe.
Answer:
√2·3^√2
Step-by-step explanation: