1. a music store marks up the instruments it sells by 30%. a. if the store bought a guitar for $45, what will be its store price? b. if the price tag on a trumpet says $104, how much did the store pay for it? c. if the store paid $75 for a clarinet and sold it for $100, did the store mark up the price by 30%?

A.  $58.50

B.  $80

C.  No. The markup was 33 1/3%

Step-by-step explanation:

You are expected to know the relevant relationship is ...

   cost + markup = selling price . . . . also called "store price" in this problem

___

A. The markup is 30% × $45 = $13.50, so the store price is ...

  $45 + 13.50 = $58.50

___

B. When the 30% markup is added to the 100% cost, the selling price is 130% of the cost, or 1.30 times the cost. Here you have ...

  $104 = 1.30 × cost

  $104/1.3 = cost = $80 . . . . . divide by the coefficient of cost

___

C. The markup is $100 -75 = $25, so the markup percentage based on cost is ...

  $25/$75 × 100% = 33 1/3%

This is not 30%.

the answer is 15% decrease

d. 24+-0.114

step-by-step explanation:

the question requires us to calculate the approximate 95% confidence interval for the mean number of ounces of ketchup per bottle in the sample given the following statistics;

sample mean = 24

standard deviation, σ = 0.4

sample size , n = 49

the confidence interval for a population mean is calculated using the formula;

sample mean ± z-score*(σ/sqrt(n))

the z-score associated with a 95% confidence interval, from the standard normal tables, is;

1.96

substituting these values into the formula;

24 ± 1.96*(0.4/7)

= 24 ± 0.112

from the alternatives given, choice d is closest to the above expression;