Can someone please explain what they did wrong in the problem and explain how you would fix it. (8grade math)
1 answer:
You might be interested in
Answer:
0% probability that the sample mean would have been as high or higher than 3.1 if the company’s claims were true.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
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 pvalue, we get the probability that the value of the measure is greater than X.
Central limit theorem
The Central Limit Theorem estabilishes that, for a random variable X, with mean and standard deviation
, a large sample size can be approximated to a normal distribution with mean
and standard deviation
In this problem, we have that:
What is the approximate probability that the sample mean would have been as high or higher than 3.1 if the company’s claims were true?
This is 1 subtracted by the pvalue of Z when X = 3.1. So
By the Central Limit Theorem
has a pvalue of 1.
1 - 1 = 0
0% probability that the sample mean would have been as high or higher than 3.1 if the company’s claims were true.
Answer:
x = 32 y = 16 z = 64
Step-by-step explanation:
x is the 1st number
y is the 2nd number
z is the 3rd number
The first number is twice the second number so
x = 2 y
The third number is twice the first number.
z = 2 x
Their sum is 112
x + y + z = 112
Plus in what we know:
x + y + z = 112
2 y + y + 2x = 112
3y + 2x = 112 Let's solve for y and subtract 2x from each side
3y = 112 - 2x Divide both sides by 3
y =
Now plug our answer back in to solve for x.
x = 2y
x = 2 ( )
x = (224 - 4x) / 3 Multiply each side by 3.
3x = 224 - 4x Add 4x to each side
3x + 4x = 224
7x = 224 Divide each side by 7
7x / 7 = 224 / 7
x = 32
Now we can solve for z.
z = 2x
z = 2 ( 32 )
z = 64
Now we can solve for the numerical value of y.
x + y + z = 112
32 + y + 64 = 112
96 + y = 112 Subtract 96 from each side.
y = 112 - 96
y = 16