30 is the geometric mean between 9 and what number? show your calculations.

30 is the geometric mean between 9 and 51.

Step-by-step explanation:

i multiplied 30 by 2 because there are two numbers in the set of numbers that have a mean of 30.

30*2=60

i then subtracted 9, working back from finding the mean,

60-9=51.

check your work!

51+9=60/2=30

your answer is 51

- "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."