# need help asap?

A high school's graduating class has a mean graduating average of 63.7% with a standard deviation of 11.2%.

How many of the 460 graduates would expect to have a graduating average of 85% or higher?

Answer the question without the use of technology.

Explain what the value of the z-score associated with an average of 85% means in terms of the standard deviation

1 mark for showing work to find the probability

1 mark for correct probability

1 mark for correct number of students

1 mark for showing work to calculate the z-score

1 mark for explanation

### 1 Answer

- Anonymous1 month ago
P(>85% average) = 1 - P(≤85% average)

μ = 63.7% = 0.637

σ = 11.2% = 0.112

x = 85% = 0.85

z = (x - μ)/σ

z = (0.85 - 0.637)/0.112 = 1.90

z-score of 1.90 corresponds to 0.9713 on z-score table.

P(≤85%) = 97.13% graduates

P(>85%) = 100% - 97.13% = 2.87% graduates

2.87% of 460 graduates = 0.0287 * 460 = 13 graduates

none could have done better in explaining the method than you.