Marta hopes to have a test average of at least 90 by the end of the marking period. her grades on the first four tests have been 86, 84, 97 and 89. what is the lowest grade she can receive on her fifth and final test and still have a test average of 90 or higher?

 Marta need to score at least 94 to receive an average of 90 or higher considering all five tests.

Explanation:

 Marks received by Marta in four tests =  86, 84, 97 and 89

 Let mark received in fifth test be x

 We have average of five test is more than or equal to 90

 So we have

 So Marta need to score at least 94 to receive an average of 90 or higher considering all five tests.

x

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."