Ruby wants to find out what variables affect the rate at which sugar dissolves in water. She records different information about four containers of water and sugar, as shown in the table below. Which two containers should Ruby choose to investigate the effect that temperature has on the rate at which sugar dissolves?

The correct answer is - containers 1 and 3.

Explanation:

In any experiment or investigation, there must be all the factors should be constant other than the variable that is changed to see the effect on the result or desired character.

In this experiment to check the effect of the temperature, there must be the only temperature is a variable that should be manipulated rest should remain constant. In container 1st and 3rd, all the variable amount of sugar, the method of mixing all are the same except temperature.

Thus, the correct answer is - 1 and 3rd.

Downstream, the current is helping the swimmer go faster relative to the land.

Explanation:

As shown in the figure the resultant vector is the addition of velocity of water and velocity of swimmer.

This shows that the swimmer is in the direction along the flow of the current. Thus, answer is downwards, the current is helping the swimmer go faster relative to the land.