Math Problem Statement

Suppose Z follows the standard normal distribution. Calculate the following probabilities using the ALEKS calculator, Round your responses to at least three decimal places.

(a) P(Z> 1.65)=

(b) P (Z≤ 0.74)=

(c) P(-108 <2<2.20)=

Solution

Let's calculate the probabilities using the standard normal distribution ZZ with a mean μ=0\mu = 0 and standard deviation σ=1\sigma = 1. We'll find these probabilities step by step:

(a) P(Z>1.65)P(Z > 1.65)

  • To find this probability, we calculate the area to the right of Z=1.65Z = 1.65. Using the cumulative distribution function (CDF) for Z=1.65Z = 1.65:

    P(Z1.65)0.9505P(Z \leq 1.65) \approx 0.9505 Therefore, P(Z>1.65)=10.9505=0.0495P(Z > 1.65) = 1 - 0.9505 = 0.0495

    Answer: P(Z>1.65)0.050P(Z > 1.65) \approx 0.050

(b) P(Z0.74)P(Z \leq 0.74)

  • Here, we find the cumulative probability for Z0.74Z \leq 0.74:

    P(Z0.74)0.7704P(Z \leq 0.74) \approx 0.7704

    Answer: P(Z0.74)0.770P(Z \leq 0.74) \approx 0.770

(c) P(1.08<Z<2.20)P(-1.08 < Z < 2.20)

  • This is the probability that ZZ lies between 1.08-1.08 and 2.202.20. We calculate:

    P(Z2.20)0.9861P(Z \leq 2.20) \approx 0.9861 P(Z1.08)0.1401P(Z \leq -1.08) \approx 0.1401 Therefore, P(1.08<Z<2.20)=0.98610.1401=0.8460P(-1.08 < Z < 2.20) = 0.9861 - 0.1401 = 0.8460

    Answer: P(1.08<Z<2.20)0.846P(-1.08 < Z < 2.20) \approx 0.846

Let me know if you'd like further explanations or if you have more questions!


Here are 8 related questions you might find useful:

  1. What is P(Z>1.96)P(Z > 1.96)?
  2. How do you calculate P(Z<1.28)P(Z < -1.28)?
  3. What is the probability that ZZ lies between 0 and 1.96?
  4. How do you interpret a z-score of -1.5 in terms of probability?
  5. What is P(2<Z<0)P(-2 < Z < 0)?
  6. How do you find the area under the curve to the left of Z=1.5Z = 1.5?
  7. What is the 99th percentile of the standard normal distribution?
  8. How do you convert raw scores to z-scores in a normal distribution?

Tip: When working with probabilities involving the standard normal distribution, always remember to use symmetry properties of the normal curve to simplify calculations.