2023 PRELIM

The actual volume of petrol in a vehicle's tank.

• Continuous Variable

• Discrete Variable

• Random Variable

• Random Sampling

Identify which describes a normal random variable.

• The curve is asymptotic to the vertical axis; that is, the curve is extended indefinitely in one direction

• The mean, median, and mode are not equal and are plotted on a central point along the horizontal axis.

• Two values can describe the distribution: the mean and the standard deviation.

• The total area under the normal curve equals .1.

Which of the following is the area of the curve to the left of z= -2.85 or z -2.85?

• 50.22%

• 78.22%

• 0.22%

• 0.28%

The average expenses of Segovia family is 13,600 every half month and the standard deviation of 1,570. If their expenses are normally distributed, what is the probability of the family consuming less than 10,000 in half month?

• 4.84%

• 95.15%

• 4.85%

• 1.10%

The average weight of insects for laboratory experiment is 13.2 g with a standard deviation of 0.8 g. What is the probability of randomly selecting insects with weights between 13.2 g to 13.6 g?

• 19.24%

• 23.57%

• 23.89%

• 19.15%

The average weight of insects for laboratory experiment is 13.2 g with a standard deviation of 0.8 g. What is the probability of randomly selecting insects with weights of 14.3 g?

• 41.62%

• 37.08%

• 42.29%

• 37.49%

The mean production of factory workers is 10 product per hour with a standard deviation of 1.5 product per hour. What is the probability of finishing more than 13 products per hour?

• 2.28%

• 47.72%

• 97.72%

• 2.29%

The height of 200 plants in a garden follows a normal distribution with a mean of 72.3 cm and a standard deviation of 8.9 cm. How many plants with a height between 65 cm and 70 cm ?

• 35

• 36

• 37

• 38

If 300 students took a test in Physics and the final grades have a mean of 70 and a standard deviation of 10. If we can approximate the distribution of these grades by a normal distribution, how many students have passed the test if the passing grade is 65 ?

• 238 students

• 243 students

• 256 students

• 268 students

For a certain type of computer, the length of time between charges of the battery is normally distributed with a mean of 50 hours and a standard deviation of 15 hours. John owns one of these computers and wants to know the probability that the length of time will be between 50 and 70 hours.

• 40.82%

• 41.08%

• 42.52%

• 43.33%