Normal distribution worksheet with answers

Free printable Normal distribution worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________   Date: ____________

1.Easy
−3−2−10123zshaded area to the left of z = 0.9821

Drag z so that the shaded area under the standard normal curve, to the left of z, is 0.9821. Find z to two decimals.

A = 0.9821
z =
2.Easy
μ = 6567P = ?

The exam scores are normally distributed with mean 65 points and standard deviation 10 points. What fraction is below 67 points? Find P(X < x) as a decimal.

μ = 65σ = 10x = 67
P(X < x) =
3.Medium
192 kg187.2 kgT = X₁ + … + X₁₆?

The masses of boxes are independent and normal with mean 12 kg and standard deviation 0.8 kg. Find the probability P that the total mass of 16 of them exceeds 187.2 kg. Round z to two decimals.

μ = 12 kgσ = 0.8 kgn = 16> 187.2 kg
P =
4.Medium
85.75122.5P = ?

The IQ scores are normally distributed with mean 100 points and standard deviation 15 points. What fraction lies between 85.75 and 122.5 points? Give P as a decimal.

μ = 100σ = 15x1 = 85.75x2 = 122.5
P =
5.Hard
380420460500540580620hbottom 95%

The battery lifetimes are normally distributed with mean 500 h and standard deviation 40 h. Drag the cut-off so the shaded bottom 95% is to the left of it. Find the cut-off x.

μ = 500 hσ = 40 h95%
x = h
6.Hard
557085100115130145pointstop 20%

The IQ scores are normally distributed with mean 100 points and standard deviation 15 points. Drag the cut-off so the shaded top 20% is to the right of it. Find the cut-off x.

μ = 100 pointsσ = 15 points20%
x = points

Answer key

  1. 1. z = 2.1
  2. 2. P(X < x) = 0.5793
  3. 3. P = 0.9332
  4. 4. P = 0.7621
  5. 5. x = 566 h
  6. 6. x = 112.6 points

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