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## AP®︎/College Statistics

# Z-scores-problem

AP.STATS:

VAR‑2 (EU)

, VAR‑2.B (LO)

, VAR‑2.B.1 (EK)

, VAR‑2.B.2 (EK)

, VAR‑2.C (LO)

, VAR‑2.C.1 (EK)

Nutritionists measured the sugar content (in grams) for 32 drinks at Jake's Java coffee shop. The drinks had a mean of 18, start text, g, end text and a standard deviation of 5, start text, g, end text, and the distribution was roughly symmetric.

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- Your score was the cutoff for the top 12%. This score is known as Z= 2.0.(13 votes)
- For the challenge problem, why is the answer not 24.5? I got to the x - 20 = -4.5 and solved for x. Isn't x the amount of sugar in the drink we are observing?(3 votes)
- so from x - 20 = -4.5 => x + 20 - 20 = -4.5 + 20 => x = 20 - 4.5 => x = 15.5

I think your problem was that you added 4.5 to 20 instead of subtracting 4.5. (4.5 is Negative)(11 votes)

- challenge problem,

since z-score=(x-mean)/std dev then

(std dev*z-score)=x-mean) equals

(std dev*z-score)+mean=x

(6*-.75)+20=15.5

-4.5+20=15.5(5 votes) - I was confused what the last question was asking. Can someone explain it to me?(3 votes)
- -.75=x-20/6 You reverse the order of finding z(4 votes)

- Could I have a z score of 1.00 and be in the top 85% of my class?(4 votes)
- if the distribution is normal (bell shaped) then the mean would be at 50% and 1 sd (approx 34%) above the mean. This would put you at the 84th percentile.

if its a normal distribution then n (size of class ie population) is not relevant and does not have any impact on the z-score.(3 votes)

- Thank You very much, this was helpfull(3 votes)
- Is there a z-score but based on median, not mean?(2 votes)
- Interpret z-score in video(2 votes)
- given financial accounts, such as the profit and loss account how do I compute the Z-Score using Xcel(2 votes)
- Grab the mean of the entire data.

Do (Certain Value - Mean) / Standard Deviation(3 votes)

- Good problems! Thank you!(2 votes)