25% of a 100-gallon tank is filled with a chemical that has to be in water to keep it cool for a nuclear reactor. The scientists have to add more of the chemical to the 100 gallons to get the mixture to 40% of the total container. How much more of the chemical in its 100% form has to be added to the 100 gallons to get a 40% mixture?
Bill has 50 pieces of candy. There are 10 each of 5 different colors. The candy dish is on top of the refrigerator, so he can’t see what colors he pulls from the dish.
His sister Linda says, “I’ll bet you can’t tell me how many pieces of candy you would have to take out of the dish to make sure you had five pieces of the same color.”
Bill responded immediately with the correct answer. Can you?
Annie has nickels and dimes in her pocket. She has three times as many dimes as nickels. Her friend Brenda says, “I can write an expression that will tell me exactly the amount of money you have in your pocket when you have three times as many dimes as nickels. All I need to know is how many nickels you have, and I can show you the correct amount.”
If x equals the number of nickels, then Brenda’s expression reads:
a. x + 3x
c. x(2x + .05)
d. There is no expression.