The mean life of a television set is 119 months with a standard deviation of 13 months. If a sample of 67 televisions is randoml
y selected, what is the probability that the sample mean would differ from the true mean by less than 2 months? Round your answer to four decimal places.
1 answer:
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Answer: see proof below
<u>Step-by-step explanation:</u>
Use the Double Angle Identity: cos 2A = 2cos²A - 1
Use the Difference Identity: cos (A - B) = cosA · cosB + sinA · sinB
Use the Unit Circle to evaluate: cos (π/2) = 0 & sin (π/2) = 1
<u>Proof LHS → RHS</u>
LHS = RHS: sin A = sin A
