36 , if I’m wrong i am so sorry but its the only number that can fit!
This can be solved using the formula for t test which is = x - mu over standard deviation divided by the square root of the number of samples. In this case, it is 1185 - 1200 over 70 divided by square root of 100 which give us a value of 2.14 which is equal to .9839 in area. Only rarely, just over one time in a hundred tries of 100 light bulbs, would the average life exceed 1200 hours.
Be more specific. Like what is it asking you to do ? I'm trying to help. :)
Answer: The answer to complete the sentence should be D).
Ok, so 3 and 10, remember that, then remember 1 and 2. Subtract them both, and that will be your average speed.
