Sixty percent of the flowers in Karen’s garden are roses. Which of the following shows 60% roses?
1 answer:
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Answer:
61 commuters must be randomly selected to estimate the mean driving time of Chicago commuters.
Step-by-step explanation:
Given : We want 95% confidence that the sample mean is within 3 minutes of the population mean, and the population standard deviation is known to be 12 minutes.
To find : How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters?
Solution :
At 95% confidence the z-value is z=1.96
The sample mean is within 3 minutes of the population mean i.e. margin of error is E=3 minutes
The population standard deviation is s=12 minutes
n is the number of sample
The formula of margin of error is given by,
Substitute the value in the formula,
Squaring both side,
Therefore, 61 commuters must be randomly selected to estimate the mean driving time of Chicago commuters.
Answer:
6
Step-by-step explanation:
Deisha's build rate = 1 fence per 15 hours = 1/15 fences per hour
Travis's build rate = 1 fence per 12 hours = 1/12 fences per hour
Working together, their combined rate is 1/15 + 1/12 = 3/20 fences per hour
So it takes them 20/3 = 6 2/3 hours per fence