Using the normal approximation to the binomial distribution, it is found that:
a) 0.242 = 24.2% probability of getting 717 or more peas with red flowers.
b) Since Z < 2, 717 peas with red flowers is not significantly high.
c) Since 717 peas with red flowers is not a significantly high result, we cannot conclude that the scientist's assumption is wrong.
For each pea, there are only two possible outcomes. Either they have a red flower, or they do not. The probability of a pea having a red flower is independent of any other pea, which means that the binomial distribution is used to solve this question.
Binomial distribution:
Probability of x successes on n trials, with p probability.
Normal distribution:
In a normal distribution with mean
and standard deviation
, the z-score of a measure X is given by:
- It 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, which is the percentile of X.
- If Z > 2, the result is considered <u>significantly high</u>.
If
and
, the binomial distribution can be approximated to the normal with:
![\mu = np](https://tex.z-dn.net/?f=%5Cmu%20%3D%20np)
![\sigma = \sqrt{np(1-p)}](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%5Csqrt%7Bnp%281-p%29%7D)
In this problem:
- 943 peas, thus,
![n = 943](https://tex.z-dn.net/?f=n%20%3D%20943)
- 3/4 probability of being red, thus
.
Applying the approximation:
![\mu = np = 943(0.75) = 707.25](https://tex.z-dn.net/?f=%5Cmu%20%3D%20np%20%3D%20943%280.75%29%20%3D%20707.25)
![\sigma = \sqrt{np(1-p)} = \sqrt{943(0.75)(0.25)} = 13.297](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%5Csqrt%7Bnp%281-p%29%7D%20%3D%20%5Csqrt%7B943%280.75%29%280.25%29%7D%20%3D%2013.297)
Item a:
Using continuity correction, this probability is
, which is <u>1 subtracted by the p-value of Z when X = 716.5</u>.
Then:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![Z = \frac{716.5 - 707.25}{13.297}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B716.5%20-%20707.25%7D%7B13.297%7D)
![Z = 0.7](https://tex.z-dn.net/?f=Z%20%3D%200.7)
has a p-value of 0.758.
1 - 0.758 = 0.242
0.242 = 24.2% probability of getting 717 or more peas with red flowers.
Item b:
Since Z < 2, 717 peas with red flowers is not significantly high.
Item c:
Since 717 peas with red flowers is not a significantly high result, we cannot conclude that the scientist's assumption is wrong.
A similar problem is given at brainly.com/question/25212369