Z- score multiple choice Assignment

1. Mr. Green Fatigues is in the 85th percentile in his class with respect to grades. This means,

• 85% of the class is smarter than him.
• He is smarter than 85% of the class.
• He has an 85% average.
• The class average is 85%

2. Suppose a random variable has a z-score of -1.75, a standard deviation of 8 and X = 12. Then the mean of X is,

• -26
• 6
• -6
• 26

1. Suppose the masses of Megalodons are normally distributed with a mean of 47,000 kg and a standard deviation of 2,500 kg. Approximately how many, in a group of 175 megalodons, have a mass of more than 51,375 kg?

• 0.9599
• 168
• 167.98
• None of the above.

4. If there are 250 snarks in a colony (a snark is an imaginary animal) and their masses are normally distributed with a mean of 1.8 grams and a standard deviation of 0.5 grams. Approximately how many would have a mass between 1.75 grams and 1.875 grams?

• 0.4009
• All of them
• 100
• 0.5596

5. If we say tat P(Z < a) = 0.9370 this means that z = a is,

• Greater than 6.3 % of other z values
• Less than 93.7% of other z values
• Less than 6.3% of other z values
• Greater than 93.7% of other z values

6. If X~N(15, 25) and x = 17, then x is,

• 1.7 standard deviations above the mean
• 0.4 standard deviations below the mean
• 0.4 standard deviations above the mean
• None of the above

7. Suppose X~N(15, 25), then P(X < 22.5) =

• 0.9332
• 0.9938
• 1.5
• 0.5

8. If P(Z < z) = 0.1075, then z =

• 0.1075
• 0.8925
• 1.24
• -1.24

9. If the mean for X is 50 and the standard deviation for X is 12.5, then z = 1.5 would mean x =

• 55.25
• 51.5
• 68.75
• None of the above

10. The heights of Lawn Trolls are normally distributed with a mean of 35 cm and a standard deviation of 5 cm. If there are 95 Trolls in a lawn, approximately how many are between 32.5 cm and 37.5 cm tall?

• 0.6915
• 36
• 66
• 29