Let x be his score on the last test so that to get an average of 90
His to average score at year end (4 terms), including the last is:
(92 +94 + 98 + x)/4 =90
(92 +94 + 98 + x) =4 x 90
x = - 274 + 360
x= 86
Step - 1: Calculate 20% of 840.

Step - 2: Subtract from 840.

When solving a problem, a tree diagram depicts the order in which events must be completed.
<h3>What is the relevance of a tree diagram?</h3>
Tree diagrams are very effective in probability because they clearly and simply record all likely scenarios.
The attached Tree Diagram has been used to depict the problem that John is trying to solve.
Learn more about Tree diagrams at:
brainly.com/question/2581880
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Step-by-step explanation:
Joe's climbing rate is not constant
3 × 2 = 6
8 × 1.5 = 12
12 × 1.1666666667 = 14
Time when climber reaches 30ft is unknown because climbing rate is not constant
Zas's climbing rate is 2.5
2 × 2.5 = 5
4 × 2.5 = 10
12 × 2.5 = 30
At 12 seconds, Zas reaches 30 feet.
Stephen's climbing rate is 4
2 × 4 = 8
4 × 4 = 16
6 × 4 = 24
30 ÷ 4 = 7.5
7.5 × 4 = 30
At 7.5 seconds, Stephen reaches 30 feet.
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