This is the formula for percentage increase and decrease
The missing factor is (a -1) I believe. If you foil (5a + 9)(a - 1) you would get 5a^2 + 4a - 9.
Answer:
The data item is 
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Mean of 400 and a standard deviation of 60.
This means that 
z=3
We have to find X when Z = 3. So




The data item is 