CFA CFA Level 1 Common Probability distribution

Common Probability distribution

  • This topic has 2 replies, 2 voices, and was last updated Nov-20 by fmccray.
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    • fmccray
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      Hello- Need help with this question please. I am not sure where the answer is 3.59%.

      Thank you for taking a look in advance.

      Cumulative z-table:

      z 0.00 0.01 0.02 0.03

      1.6 0.9452 0.9463 0.9474 0.9484

      1.7 0.9554 0.9564 0.9573 0.9582

      1.8 0.9641 0.9649 0.9656 0.9664

      Monthly sales of hot water heaters are approximately normally distributed with a mean of 21 and a standard deviation of 5. What is the probability of selling 12 hot water heaters or less next month?

      I picked 0.9641. i was wrong. it is 3.59% (Where did they calculate 3.59%)

    • djriv81
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      You were close to getting this one.

      Short version is you needed to do 1-0.9641 = 0.0359

      96.41% represents the probabilty of selling 12 hot water heaters or MORE. The question calls for 12 or Less.

      Always best to draw graphs on these to give yourself a visual.

    • fmccray
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      OMG. 🤦‍♀️

      I truly appreciate your help.

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