A researcher does a study of a mathematics program in a one-group pretest-posttest design. She gives the group of second graders a multiple-choice pretest. Unknown to her, the children had never taken a multiple-choice test. The children scored higher on the same test given at posttest. She argues that the children improved because of the mathematics program. That the children had never taken a multiple-choice test before and showed improvement at posttest suggests that one possible threat to her conclusion is a:

Paula makes stained-glass windows and sells them to boutique stores. if her costs total $12,000 per year plus $4 per window for the frame. how many windows must she produce to earn a profit of at least $48,000 in one year if she sells the windows for $28 each? 1. define a variable for the situation. 2. write an inequality that represents her profit. note: revenue is money coming in. cost is money going out. profit is the difference between the revenue and the cost. in other words: revenue - costs profit 3.using words, describe how many windows she must sell to have a profit of at least $48,000.