At the kennel , there are 6 dogs for every 5 cats what is the ratio of dogs to cats
2 answers:
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Answer:
Probability that a randomly selected woman's gestation period will be between 261 and 279 days is 0.68.
Step-by-step explanation:
We are given that the average human gestation period is 270 days with a standard deviation of 9 days. The period is normally distributed.
Firstly, Let X = women's gestation period
The z score probability distribution for is given by;
Z = ~ N(0,1)
where, = average gestation period = 270 days
= standard deviation = 9 days
Probability that a randomly selected woman's gestation period will be between 261 and 279 days is given by = P(261 < X < 279) = P(X < 279) - P(X 261)
P(X < 279) = P( <
) = P(Z < 1) = 0.84134
P(X 261) = P(
) = P(Z
-1) = 1 - P(Z < 1)
= 1 - 0.84134 = 0.15866
<em>Therefore, P(261 < X < 279) = 0.84134 - 0.15866 = 0.68</em>
Hence, probability that a randomly selected woman's gestation period will be between 261 and 279 days is 0.68.
Answer:
The sample size needed is 2401.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error of the interval is:
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
Estimate the sample size needed if no estimate of p is available so that the confidence interval will have a margin of error of 0.02.
We have to find n, for which M = 0.02.
There is no estimate of p available, so we use
The sample size needed is 2401.