Twelve ping-pong balls are in a bag. Ten are white and two are orange. Find the probability that the two orange ping-pong balls
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Ideal timeline of the dance routine = 4 minutes = 4 × 60 seconds = 240 seconds
Variation allowed in the dance routine timeline = +- 5 seconds
Let the timeline of the dance routine be T
⇒ 240 seconds - 5 seconds < T < 240 seconds + 5 seconds
⇒ 235 seconds < T < 245 seconds
⇒ minutes < T <
minutes
⇒ 3.92 minutes < T < 4.08 minutes
So the least possible time of the dance routine can be 3.92 minutes (or 235 seconds) and the greatest possible time of the dance routine can be 4.08 minutes (or 245 seconds)
Answer:
And rounded up we have that n=99
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Solution to the problem
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by and
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
We assume the value for since we don't have previous info. And replacing into equation (b) the values from part a we got:
And rounded up we have that n=99