Answer:
95.64% probability that pledges are received within 40 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:

What is the probability that pledges are received within 40 days
This is the pvalue of Z when X = 40. So



has a pvalue of 0.9564
95.64% probability that pledges are received within 40 days
1. Stock Market:
If a stock price decreased $2 per day for four days, then the total change in value of the stock is $8. (2 x 4)
Answer: $8.
2. Evaporation:
With the given information, we can infer that if 3 inches of water in a tank decreases each week, then 15 inches of water would decrease over the course of 5 weeks. (3 x 5)
Answer: 15 inches.
3. Football:
If a football team lost 9 yards on 3 consecutive plays, then the team's total change in position is 27 yards. (9 x 3)
Answer: 27 yards.
Hope this helps! Good luck.
It's A, increased by a factor of 6.