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Answer:
The cost of soft pretzel is $1.25
Step-by-step explanation:
Let $x be the price of one slice of pizza and $y be the price of one soft pretzel.
1. 9 slices of pizza cost $9x and 5 soft pretzels cost $5y. Together they cost $33.25, then
9x+5y=33.25.
2. 4 slices of pizza cost $4x and 6 soft pretzels cost $6y. Together they cost $19.50, then
4x+6y=19.50.
3. Solve the system of two equations:
Multiplythe first equation by 4, the second equation by 9 and subtract them:
Then
Answer:
a) 0.18% of cold sufferers experience fewer than 4 days of symptoms
b) 64.40% of cold sufferers experience symptoms for between 7 and 10 days.
Step-by-step explanation:
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.
In this problem, we have that:
a. What proportion of cold sufferers experience fewer than 4 days of symptoms?
This is the pvalue of Z when X = 4. So
has a pvalue of 0.0018.
So 0.18% of cold sufferers experience fewer than 4 days of symptoms.
b. What proportion of cold sufferers experience symptoms for between 7 and 10 days?
This is the pvalue of Z when X = 10 subtracted by the pvalue of Z when X = 7. So
X = 10
has a pvalue of 0.9812.
X = 7
has a pvalue of 0.3372.
So 0.9812 - 0.3372 = 0.644 = 64.40% of cold sufferers experience symptoms for between 7 and 10 days.