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A day care program has an average daily expense of $75.00. The standard deviation is $5.00. The owner takes a sample of 64 bills. What is the probability the mean of his sample will be between $70.00 and $80.00? Step 1. Calculate a z-score for $70.00 - Step 2. Give the probability for step 1. % Step 3. Calculate the z-score for $80.00 + Step 4. Give the probability for step 3. % Step 5. Add the probabilities from steps 2&4. have to pick out of all 3 answers for all 3 problems a.) 30 b.) 68 c.) 1.0 d.) 34

Respuesta :

Answer:   B 68

Step-by-step explanation:

x is a raw score to be standardized;

μ is the mean of the population;

σ is the standard deviation of the population.

Therefore the mean is zero. Seventy is -1z, or -1 standard deviation.

Step 2: 34.13% of the cases fall between -1 standard deviation and the mean. Thus there is a 34.13% chance that the score will fall between 70 and 75. This, of course, assumes a normal curve.

Step 3: An 80 is +1z or +1 standard deviation assuming a normal curve.

Step 4: Thirty four percent of the cases fall between +1 standard deviation and the mean. Thus there is a 34.13% chance that the score will fall between 75 and 80. This, of course, assumes a normal curve.

Step 5: Score between +1z and -1z, or +1 and -1 standard deviation account for 68.26% of the cases.

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