# Stat Help!?

Find the following probabilities for the standard normal random variable z:

(a) P(−1.68≤z≤2.23)=

(b) P(−0.97≤z≤2.01)=

(c) P(z≤0.27)=

(d) P(z>−1.45)=

How do I go about figuring these out? I'm so confused and my professor isn't much help.

### 4 Answers

- AlanLv 72 months agoFavorite Answer
since you figured out the last two.

P( A<z<B) = P(z<B) - P(z<A)

a) P(−1.68≤z≤2.23)=

so this becomes

P(−1.68≤z≤2.23)= P(z< 2.23) - P(z< -1.68)

so you now just need to find

P(z< 2.23) and P(z< -1.68)

(b) P(−0.97≤z≤2.01)=

P(−0.97≤z≤2.01) = P(z< 2.01) - P(z< -0.97)

again you should know how to find

P(z<2.01) and P(z< -0.97)

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- 2 months ago
I'm sending you the answer for the first one, you need to add the probabilities seen in the attached picture i.e. 45.35% + 48.71% = 94.06%

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- alexLv 72 months ago
Just know how to input data in your calculator

a/

0.9406

b/

0.8118

c/

0.6064

d/

0.9265

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- MaryLv 42 months ago
you need to look at a z-score table. find the values in the table and you will have your answers.

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- MaryLv 42 months agoReport
You have to write it the same way as it is written. You're just stating that the z score is within the values , its not a specific value, but a value within two others

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