50 numbers are written in a row. Every number starting with the third equals the sum of all the preceding numbers. What will you get if you divide the 23rd number by the 15th?

Assume the first two numbers are A and A

The row will be

A, A, 2A, 4A, 8A

For the nth number in the list it can be represented in the way number= for any n≥3

Using this formula the answer of the question can be obtained with division of the 23th and 15th term

Simplify

=

=

=

=

=256

Done!

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."

step-by-step explanation: