There are three questions below，

refer to the following graph.

For which two uses of electricity was the ratio of the amounts of electricity used most nearly 3 to 1?

The electricity used by the water heater was measured separately and its cost per kilowatt-hour was one-half the cost per kilowatt-hour of the rest of the electricity used. The cost of the electricity used by the water heater was most nearly what fraction of the total cost of all the electricity used?

In November the Smythe household used the same total amount of electricity as in July, but the water heater used 33 percent of this total amount. By approximately what percent did the amount of electricity used by the water heater increase from July to November?