The lengths of iron rods produced by a machine is assumed to have a Normal distribution with a mean of 5 cm and a standard deviation of 2cm. A sample of 4 rods is selected at random for inspection. What should be the probability that the mean length of the 4 rods is less than 5.2cm

70.30

step-by-step explanation:

explanation:

step-by-step explanation:

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.

2/3=10/15

1/5=3/15

10+3=13/15

2 13/15 is the answer