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.
Answer:
17/40
Step-by-step explanation:
First let's find the least common denominator. The denominators are 8 and 25 so we need to find the least common multiple of 8 and 25.
8=2*2*2
25=5*5
Since they share no common factors the least common multiple of 8 and 25 is 8*25 which is 200.
Now we convert the fractions:
5/8*25/25=125/200
5/25*8/8=40/200
Then we subtract:
125/200-40/200=85/200
Now we simplify it:
17/40
