Answer:
a) 6.68th percentile
b) 617.5 points
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) A student who scored 400 on the Math SAT was at the ______ th percentile of the score distribution.



has a pvalue of 0.0668
So this student is in the 6.68th percentile.
b) To be at the 75th percentile of the distribution, a student needed a score of about ______ points on the Math SAT.
He needs a score of X when Z has a pvalue of 0.75. So X when Z = 0.675.




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Answer: the number of shoppers on the first day is 125
Step-by-step explanation:
The number of shoppers is 20% more than the numbers of shoppers the day before. It means that the number of shoppers is increasing in geometric progression. The formula for determining the sum of n terms, Sn of a geometric sequence is expressed as
Sn = (ar^n - 1)/(r - 1)
Where
n represents the number of term in the sequence.
a represents the first term in the sequence.
r represents the common ratio.
From the information given,
r = 1 + 20/100 = 1.2
n = 4(first 4 days)
S4 = 671
Therefore, the expression for the first 4 days is
671 = (a × 1.2^(4) - 1)/1.2 - 1
671 = (a × 1.2^(4) - 1)/0.2
671 = 1.0736a/0.2
671 = 5.368a
a = 671/5.368
a = 125
Answer:
The balance of Dianne's register should be $359.41
Step-by-step explanation:
We can begin at the ending balance on the bank statement at $578.30
Then a check is written for $219.25, so a debit
Next a deposit is made for $140.36, so a credit
Then a withdrawal is made for $140.00, so a debit
This means we can make the equation
