Ella's test grades in her history class are 89, 94, 82, 84, and 98. What score must Ella make on her next test to have a mean
test score of 90?
needed on the next test

93

Step-by-step explanation:

set the test score she needs as x.

the mean is 90, so 89+94+82+84+98+x=90*6=540. solving this, we get x=93

93

Step-by-step explanation:

To calculate mean you sum the score of all of the test scores and divide that by the number of tests. We can use this formula to work backwards from the mean 90.

If the mean of 6 tests is 90 that means the combined total of all the scores is equal to 90 * 6 which is 540. Right now the total of Ella's 5 test grades is 447.

If you subtract 447 from 540, the result will be the test score needed to get a mean of 90.

540 - 447 = 93

histogram or dot plot?

step-by-step explanation:

- "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."