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

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  • Alan
    Lv 7
    2 months ago
    Favorite 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%

    Attachment image
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  • alex
    Lv 7
    2 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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  • Mary
    Lv 4
    2 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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    • Mary
      Lv 4
      2 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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