On a sample tray, 6 out of 20 cake samples are chocolate.

Mathematics

1 answer:

Dahasolnce [82]2 years ago

7 0

Answer:

6/20 = 30%

30% is the probability that a randomly selected piece of cake will be chocolate

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How many hours would someone who earns $7.50 per hour have to work to earn $116.25?

Reil [10]

Answer:

15.5 hours

Step-by-step explanation:

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5 0

2 years ago

Assume that females have pulse rates that are normally distributed with a mean of beats per minute and a standard deviation of b

snow_tiger [21]

Answer:

a) This is the p-value of Z when X = A subtracted by the p-value of Z when X = B.

b) P-value of Z when X = 76 subtracted by the p-value of X = 68.

c) Because the underlying distribution(pulse rates of females) is normal.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this question:

Mean $\mu$ , standard deviation $\sigma$ .

standard deviation of beats per minute.

a. If 1 adult female is randomly selected, find the probability that her pulse rate is between A beats per minute and B beats per minute.

This is the p-value of Z when X = A subtracted by the p-value of Z when X = B.

b. If 4 adult females are selected, find the probability that they have pulse rates with a mean between 68 beats per minute and 76 beats per minute.

Sample of 4 means that we have $n = 4, s = \frac{\sigma}{\sqrt{4}} = 0.5\sigma$