I'm not sure but I think it would be 10 pens hope this helps.
Answer:
b. The values X and Y are independent therefore, the mean is 34 seconds and the standard deviation is 50 seconds
Step-by-step explanation:
Subtraction between normal variables:
When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.
Before the training, the mean running time for the students to run a mile was 402 seconds with standard deviation 40 seconds.
This means that 
After completing the program, the mean running time for the students to run a mile was 368 seconds with standard deviation 30 seconds.
This means that 
Which of the following is true about the distribution of X-Y?
They are independent, so:


This means that the correct answer is given by option b.
<span>Total mass contains 320g copper. How many parts of 16g copper are there of the total mass of 320g copper? 320/16 = 20. There are 20 portions of 16g copper.
(320/16) * 3 = 60g
There are 60g of zinc in the compound.</span>
Answer:
C
Step-by-step explanation:
It would be -12 to go to the last cube so u subtract 12 from every number then multiply the numbers
5678(1+(0.045×6))
5678=P as it is the principal amount