X is normal with mean 250 g and standard deviation 4 g; Y is independent and normal with mean 500 g and standard deviation 9 g. Find the standard deviation σ of the difference X − Y.
Normal distribution worksheet with answers
X is normal with mean 12 min and standard deviation 1.5 min; Y is independent and normal with mean 20 min and standard deviation 2 min. Find the standard deviation σ of the difference X − Y.
The bag weights are normally distributed with mean 250 g and standard deviation 5 g. What fraction lies between 242.5 and 260.25 g? Give P as a decimal.
X is normal with mean 12 min and standard deviation 1.5 min; Y is independent and normal with mean 20 min and standard deviation 2 min. Find the probability P that X + Y is more than 37 min. Round z to two decimals.
The heights of adult men are normally distributed with mean 178 cm and standard deviation 7 cm. Drag the cut-off so the shaded top 85% is to the right of it. Find the cut-off x.
The exam scores are normally distributed with mean 65 points and standard deviation 10 points. Drag the cut-off so the shaded top 30% is to the right of it. Find the cut-off x.
Answer key
- 1. σ = 9.849 g
- 2. σ = 2.5 min
- 3. P = 0.913
- 4. P = 0.02275
- 5. x = 170.7 cm
- 6. x = 70.2 points
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