The leader Fulgencio Batista maintained control of Cuba from 1934 to 1959.
Answer: B. Fulgencio Batista
The answer would be D, negative acceleration
Answer: 17cm.
Explanation:
The equation you're using is:
Δd = df - di
Which means the change in position is equal to the final position minus the starting position. In this case that works out to 20cm - 3cm = 17cm. We're only interested in how much the snail moved, not how long it took to move, so even though they give a time it actually doesn't matter for this question.
The diagram is missing; however, we know that the intensity of a sound wave is inversely proportional to the square of the distance from the source:

where I is the intensity and r is the distance from the source.
We can assume for instance that the initial distance from the source is r=1 m, so that we put

The intensity at r=3 m will be

Therefore, the sound intensity has decreased by a factor

.
There are some more like Time - second (s)
Amount of substance - mole (mole)
Electric current - ampere (A)
Temperature - kelvin (K)
Luminous intensity - candela (cd)