Which of the following statements is$/$are true?

Question $4$ options:

$1)$

Under the cost$-$oriented method, the retail price is determined by adding a fixed percentage to the cost of the merchandise.

$2)$

With the demand$-$oriented method, prices are based on what customers expect or are willing to pay.

$3)$

The keystone method of setting price involves doubling the cost of the merchandise to obtain the initial retail selling price.

$4)$

All of these statements are true.

$5)$

None of these statements are true.