Before the summer season begins, you need to decide how many postcards to stock in your shop. Historically, the number of postcards you sell during the summer season has approximately a normal distribution with mean 50 and standard deviation 7 (in thousands of postcards). If you want to be approximately 80% sure that you can meet demand, how many postcards should you stock

You should stock 59 thousands of postcards

Step-by-step explanation:

In the standard normal distribution table, you want to find the Z with probability 0.4, which is (see figure attached) 1.28. Z is calculated as follows:

Z = (x - μ)/σ

where μ is the mean and σ is the standard deviation. Replacing with data:

1.28 = (x - 50)/7

x = 1.28*7 + 50 = 59 thousands of postcards

So, approximately 80% of the demand would be satisfied with a number of postcards between 41000 and 59000 (notice the curve is symmetrical).

i dont know sorry

step-by-step explanation:

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870