Drag z so that the shaded area under the standard normal curve, to the left of z, is 0.9693. Find z to two decimals.
Normal distribution worksheet with answers
X and Y are independent normal variables for the mass of a filled jar: jar plus contents: X has mean 250 g and standard deviation 4 g, Y has mean 500 g and standard deviation 9 g. Find the standard deviation σ of X + Y.
The IQ scores are normally distributed with mean 100 points and standard deviation 15 points. What fraction lies between 100 and 103 points? Give P as a decimal.
Drag z so that the shaded area under the standard normal curve, to the right of z, is 0.0170. Find z to two decimals.
Hole diameters D are normal with mean 25.04 mm and standard deviation 0.01 mm. Shaft diameters d are independent and normal with mean 25 mm and standard deviation 0.02 mm. A randomly chosen shaft fits when D − d > 0. Find the probability P that it fits. Round z to two decimals.
The heights of adult men are normally distributed with mean 178 cm and standard deviation 7 cm. Find the value x below which 95% of them lie (the 95th percentile).
Answer key
- 1. z = 1.87
- 2. σ = 9.849 g
- 3. P = 0.07926
- 4. z = 2.12
- 5. P = 0.9633
- 6. x = 189.5 cm
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