You put mass m1 of ice cooled to -20C into mass m2 of water at 2C. Both are in a thermally insulated chamber. In the final state of the system: A. Everything turns to ice at a temperature below 0C. B. Everything melts and is at a temperature above 0C. C. There is a mixture of water and ice as the final state. D. The water and ice never reach the same temperature. E. There is not enough information to find the final temperature.

E. There is not enough information to find the final temperature.

Explanation:

We do not the actual masses of ice and water involved in the question, so we cannot determine if the water freezes or the ice melts. So, there is not enough information to find the final temperature.

what was the answer?

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form