Answer:
The standard deviation is 7.7
Step-by-step explanation:
Problems of normally distributed samples can be 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:

8 percent of the scores are above 89
This means that X = 89 has a pvalue of 1 - 0.08 = 0.92. So when Z = 89, Z = 1.405.





The standard deviation is 7.7
To subtract fractions, we need a common denominator, which would be 10. To do this, multiply 3/5 by 2
3 * 2 = 6
5 * 2 = 10
Now subtract
A 15% percent markup means that the typewriter cost was increased by 15%, or 0.15 by moving the decimal 2 places to the left. If the original price was x, and 15% of it is 0.15*x, we can add them up to get 1.15*x=129.95. Dividing both sides by 1.15, we get x=113 dollars
Trust me it is A) because 92.365- 30.517 is equal to 61.848