7/8
3/10 of 7/8 means 3/10 times 7/8=21/80
1hour=60mins
60 times 21/80=1260/80=15.75
answer is 15.75 mins
Question:
If a sample of 2 hammer is selected
(a) find the probability that all in the sample are defective.
(b) find the probability that none in the sample are defective.
Answer:
a 
b 
Step-by-step explanation:
Given
--- hammers
--- selection
This will be treated as selection without replacement. So, 1 will be subtracted from subsequent probabilities
Solving (a): Probability that both selection are defective.
For two selections, the probability that all are defective is:




Solving (b): Probability that none are defective.
The probability that a selection is not defective is:

For two selections, the probability that all are not defective is:




Answer:that would be 18
Step-by-step explanation:
The probability is (1/6)^5 power. Since the locks are independent of each other, you can multiply the probabilities together. There are 6 possible numbers for each lock and there are 5 locks. So the probability is (1/6)^5 power.<span />
15=-4+z/3
+4 +15 = +4 -4 +z/3
cancels the 4 on the right side
19 = z/3
3 x 19 = z/3 x 3
cancels 3 on the right side
I think the answer is z = 57