Give the step-by-step reasoning process and then the final answer. Jenna is adding black dots to a bunch of white blouses. Each blouse gets 20 dots, and each dot takes 10 ml of black dye. How many 400-ml bottles of dye does Jenna need to buy to dye 100 blouses?
First find the amount of dye each blouse takes: 20 dots / blouse * 10 ml / dot = 200 ml / blouse. Then multiply the dye used per blouse by the number of blouses to find the total amount of dye used: 200 ml / blouse * 100 blouses = 20000 ml. Then divide the amount of dye needed by the amount of dye per bottle to find the number of bottles needed: 20000 ml / 400 ml / bottle = 50 bottles.
The final answer: 50.