00:01
Hello student given that the company produces refrigerator motors and engines have normal distribution with mean mu 19 .4 and with standard deviation sigma is equals to 4 .8 years.
00:20
Now service life follows normal distribution or service life normally distributed.
00:27
So for the first bit we have to find out probability that engine operating, less than 12 years.
00:34
So here we have to calculate probability of x less than 12.
00:40
So here 3 is equal to 12 minus 19 .4 divided by 4 .8 which is equal to minus 1 .516.
00:59
Now probability of z less than minus 1 .554 is equals to 0 .0617.
01:15
Therefore, probability of x less than 12 is equals to 0 .06.
01:26
Now for the next bit, we have to find out what is the probability that engine operate more than 25 years.
01:35
So here we have to find out probability of x greater than 25.
01:41
So here probability of x greater than 25 is equal to z is equal to 25 minus 19 .4 divided by 4 .8, which is equal to 1 .66.
02:00
6.
02:01
Now probability of said greater than so here probability of said greater than 1 .66 is equals to 1 minus probability of said less than 1 .66 which is equal to 0 .4515 so 1 minus 0 .455...