You are riding in an enclosed train car moving at 90 km/h. if you throw a baseball straight up, where will the baseball land?

a. in front of you.
b. in your hand.
c. behind you.
d. can't decide from the given information.

b. In your hand

Explanation: The objects from an outer perspective are moving at 90km/h all of them, even if there was a fly flying around in the train. Then if there is no change of speed of the train the moment the ball leaves the hand its relative speed with respect to the hand is zero (0), then it will land in the hand again. So the only way for it not to happen is either you move the hand or the train changes its speed, therefore the relative speed of the

ball with respect to the hand would be differente from zero and further information would be required, but since it is not stated that neither the train accelerates nor the hand is going to be moved, we can affirm the ball will land in the hand.

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