The average middle-distance runner at a local high school runs the mile in 4.5 minutes, with astandard deviation of 0.3 minute. What is the probability that a runner will run the mile in less than 4 minutes?

Possible Answers:
A)7%B)3%C)5%D)4%

How do I plug this into my TI-83 calculator? the answer is C, but I'm having trouble getting it.

Find the probability of the indicated result. Use the normal curve approximation to the binomial distribution.16)A 56-question multiple choice test has 4 possible answers for each question and a student choose the answers to each problem at random. A student selects 16 correct answers.

A)0.118 B)0.102 C)0.378 D)0.126

How do I solve this by using the binomcdf function on my calculator? I have TI-83.

The answer is suppose to be B.

To solve this probability question using a TI-83 calculator, you can utilize the normal distribution function, which is denoted as "normalcdf" on the calculator.

1. Subtract the mean from the time you want to find the probability for: 4 minutes - 4.5 minutes = -0.5 minute.

2. Divide the result from step 1 by the standard deviation: -0.5 minute / 0.3 minute = -1.67.

3. Use the "normalcdf" function on the calculator to find the probability. Press the following buttons on your calculator in this order:
- Second (2nd)
- VARS (DISTR)
- Scroll down and select 2: normalcdf

4. Enter the lower bound as -10 (a very small negative number to essentially consider negative infinity for practical purposes).

5. Enter the upper bound as the result from step 2, i.e., -1.67.

6. Enter the mean as 0 (since we assumed a standard normal distribution).

7. Enter the standard deviation as 1 (again, assuming a standard normal distribution).

8. Press ENTER to calculate the probability.

The calculator will display the probability that a runner will run the mile in less than 4 minutes. In this case, the answer should be around 5%. Therefore, the correct answer is C) 5%.