Agrocery store sells american cheese for $3.89 per pound about how much would a dollar in 1.89 pounds of cheese cost

To find the answer you need to figure out what to pultiply times one pound to get 1.89 pounds. which would be 1.89. 
Since 1 pound is 3.89
1.89 pounds times 3.89=7.35
so your answer would be 7.35