Answer:
And if we solve for a we got
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the hourly rates of a population, and for this case we know the distribution for X is given by:
For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.80 of the area on the left and 0.20 of the area on the right it's z=0.842. On this case P(Z<0.842)=0.8 and P(z>0.842)=0.20
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
Answer: 8
Step-by-step explanation:
Answer:
-72rs
Step-by-step explanation:
Y - 3x = 7 . . . . . . . . (1)
21 + 9x = 3y . . . . . .(2)
From (1), y = 3x + 7
substituting for y into (2), we have
21 + 9x = 3(3x + 7) = 9x + 21
0 = 0
Therefore, the system has an infinte number of solutions.
Answer:
I invested $ 10,000 at 7% per year, and $ 1,000 at 3% per year.
Step-by-step explanation:
Given that I invested $ 11,000 in two accounts paying 3% and 7% annual interest, respectively, if the total interest earned for the year was $ 730, to determine how much was invested at each rate, the following calculation must be performed:
5,000 x 0.07 + 6,000 x 0.03 = 530
8,000 x 0.07 + 3,000 x 0.03 = 650
10,000 x 0.07 + 1,000 x 0.03 = 730
Therefore, I invested $ 10,000 at 7% per year, and $ 1,000 at 3% per year.