Answer:
532
Step-by-step explanation:
The score that represents the top 20% = A score = 80%
Z score for 80% percentile = 0.842
We solve using the z score formula
z = (x-μ)/σ, where
x is the raw score = ??
μ is the population mean = 490
and σ is the population standard deviation = 50
Hence:
0.842 = x - 490/50
Cross Multiply
0.842 × 50 = x - 490
x = 0.842 × 50 + 490
x = 42.1 + 490
x = 532.1
Approximately = 532
Therefore, the test score = 532
D is your answer
Expand and do FOIL method (first outside inside last)
simplify and then choose right answer
A is your answer
Do the same thing
hope this helps
Answer:
21.25
Step-by-step explanation:
85/4 = 80/4+5/4 = 20 + 1 + 1/4 = 21 + 0.25 = 21.25
