Answer:
20 minutes
Step-by-step explanation:
Melissa works as fast as two Bettys, so working together, they get the job done at the rate 3 Bettys could do it. That time is (60 minutes)/3 = 20 minutes.
Working together, Betty and Melissa can mow the lawn in 20 minutes.
_____
You can also think in terms of mowing rates as lawns per minute. The total mowing rate is ...
Betty's rate + Melissa's rate = (1/60 lawns/min) +(1/30 lawns/min)
= (1/60 +2/60) lawns/min = 1/20 lawns/min
The inverse rate is then ...
20/1 min/lawn
Together, they take 20 minutes to mow 1 lawn.
Answer:6,24,36
Step-by-step explanation:
i think the ratio is 1:3
so
6:18
8:24
12:36
Answer: 95/144
Explanation:
There are 12 light bulbs.
There are 5 defective bulbs.
There are 7 not defective bulbs.
P (at least one defective) = first one defective or second one defective or both defective.
P (at least one defective) = (5/12)(7/12) + (7/12)(5/12) + (5/12)(5/12) = 95/144
Answer:
n = 7
Step-by-step explanation:
3(n - 4) = 9
3n - 12 = 9
3n = 9 + 12
3n = 21
n = 21 ÷ 3
n = 7
The correct answer is False, there is a solution.
