Emily sells erasers for $2 per package and pencils for $5 per package. she sells 220 total packages and earns $695. find the num
1 answer:
Given :
Emily sells erasers for $2 per package and pencils for $5 per package. she sells 220 total packages and earns $695.
To Find :
The number of packages of erasers and pencils that were sold .
Solution :
Let, number of erasers are x and pencils are y.
So, x + y = 220 ....1
Also, 2x + 5y = 695 ....2
Solving equation 1 and 2, we get :
x = 220 - 85 = 135
Therefore, the number of packages of erasers and pencils that were sold are 135 and 85 respectively.
Hence, this is the required solution.
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Answer:
99.99% probability that the mean weight of a 50-box case of crackers is above 16 ounces
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 normally distributed random variable X, with mean and standard deviation
, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean
and standard deviation
.
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this problem, we have that:
What is the probability that the mean weight of a 50-box case of crackers is above 16 ounces?
This is 1 subtracted by the pvalue of Z when X = 16. So
By the Central Limit Theorem
has a pvalue of 0.0001
1 - 0.0001 = 0.9999
99.99% probability that the mean weight of a 50-box case of crackers is above 16 ounces