Question

- 18

A scientist rolls two balls A and B down two different ramps. Ball A rolls 4 meters in the 1st second, 9 meters in the 2nd second, 14
meters in the 3rd second, and so on. Ball B rolls 3.5 meters in the 1st second, 6.5 meters in the 2nd second, 9.5 meters in the 3rd
second, and so on. How many meters would each ball roll in 10 seconds?
Select one
a. A: 49 m: B: 305 m
b. A: 54 m; B: 33.5 m
CA: 59 m: B: 36.5 m
d. A: 85 m: B: 72 m

Answer 1

a. A. 49m B 30.5 m

Explanation:

If I have understood the question correctly:

Ball A:

After each second the total distance travelled increases by 5 meters.

Ball A: after 10 seconds it has rolled 4 + (10-1) * 5 = 49m

Ball B: after 10 seconds it has rolled 3.5 + (10-1)* 3 = 30.5 m.

Answer 2

Option A. A: 49 m: B: 30.5 m

Explanation:

Ball A rolls 4 meters in the 1st second, 9 meters in the 2nd second, 14 meters in the 3rd second, and so on.

We can see that after each second the total distance traveled by ball increases by 5 meters.

So, we can solve this as an arithmetic sequence that is
`a+(n-1)d`

For ball A, a = 4 n = 10 d = 5

Ball B rolls 3.5 meters in the 1st second, 6.5 meters in the 2nd second, 9.5 meters in the 3rd second, and so on.

For ball B, a = 3.5 n = 10 d = 3

For ball A:

After 10 seconds, the distance will be
`4+(10-1)5`

=
`4+45` = 49 meters

For ball B:

After 10 seconds, distance covered will be
`3.5+(10-1)3`

=
`3.5+27` = 30.5 meters.

Hence, the answer is option A.