A family is relocating from St. Louis, Missouri, to California. Due to an increa

Question

A family is relocating from St. Louis, Missouri, to California. Due to an increasing inventory of houses in St. Louis, it is taking longer than before to sell a house. The wife is concerned and wants to know when it is optimal to put their house on the market. They ask their realtor friend for help and she informs them that the last 20 houses that sold in their neighborhood took an average time of 130 days to sell. The realtor also tells them that based on her prior experience, the population standard deviation is 30 days.

Construct a 90% confidence interval of the mean sale time for all homes in the neighborhood.(Round your intermediate calculations to 4 decimal places, "z" value and final answers to 2 decimal places.)

Construct a 90% confidence interval of the mean sale time for all homes in the neighborhood.(Round your intermediate calculations to 4 decimal places, "z" value and final answers to 2 decimal places.)

Explanation / Answer

Using Excel Formula

Z = normsinv(probability)

Z = normsinv(90%)

Z = 1.2816

Upper Range = Mean + SD*Z

Upper Range = 130 + 30*1.2816

Upper Range = 168.45 Days

Lower Range = Mean - SD*Z

Lower Range = 130 - 30*1.2816

Lower Range = 91.55 Days

  Confidence interval 91.55 Days to 168.45 Days

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