Math Problem Statement

Over a particular period, an asset had an average return of 11.7 percent and a standard deviation of 19.5 percent.

What range of returns would you expect to see 68 percent of the time for this asset?

Note: A negative answer should be indicated by a minus sign. Input your answers from lowest to highest to receive credit for your answers. Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.

What about 95 percent of the time?

Note: A negative answer should be indicated by a minus sign. Input your answers from lowest to highest to receive credit for your answers. Do not round intermediate calculations and enter your answers as a percent rounded to 2 decimal places, e.g., 32.16.

Solution

To determine the range of returns we would expect for this asset over a given period, we’ll use the concept of the normal distribution. For a normal distribution:

  1. 68% of observations fall within one standard deviation of the mean.
  2. 95% of observations fall within two standard deviations of the mean.

Given:

  • Average return (mean), μ=11.7%\mu = 11.7\%
  • Standard deviation, σ=19.5%\sigma = 19.5\%

68% Range

For 68% of observations, the range would be: Range=μ±σ\text{Range} = \mu \pm \sigma

Calculating the lower bound: Lower bound=11.7%19.5%=7.8%\text{Lower bound} = 11.7\% - 19.5\% = -7.8\%

Calculating the upper bound: Upper bound=11.7%+19.5%=31.2%\text{Upper bound} = 11.7\% + 19.5\% = 31.2\%

So, for 68% of the time, the expected range of returns is: [7.80%,31.20%][-7.80\%, 31.20\%]

95% Range

For 95% of observations, the range would be: Range=μ±2σ\text{Range} = \mu \pm 2\sigma

Calculating the lower bound: Lower bound=11.7%(2×19.5%)=11.7%39.0%=27.3%\text{Lower bound} = 11.7\% - (2 \times 19.5\%) = 11.7\% - 39.0\% = -27.3\%

Calculating the upper bound: Upper bound=11.7%+(2×19.5%)=11.7%+39.0%=50.7%\text{Upper bound} = 11.7\% + (2 \times 19.5\%) = 11.7\% + 39.0\% = 50.7\%

So, for 95% of the time, the expected range of returns is: [27.30%,50.70%][-27.30\%, 50.70\%]

Final Answer:

  • 68% Range: [7.80%,31.20%][-7.80\%, 31.20\%]
  • 95% Range: [27.30%,50.70%][-27.30\%, 50.70\%]

Would you like further details or have any questions?

Here are five related questions for further exploration:

  1. What would the range be for 99% of the time?
  2. How would the results change if the standard deviation were higher?
  3. What implications does a high standard deviation have on investment risk?
  4. How can understanding these ranges help in making investment decisions?
  5. What is the probability of a return below -7.8%?

Tip: When dealing with financial returns, understanding the standard deviation can help gauge potential risk, as a higher standard deviation indicates more variability around the mean.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Standard Deviation
Confidence Intervals

Formulas

Range for 68% confidence interval: Mean ± Standard Deviation
Range for 95% confidence interval: Mean ± 2 × Standard Deviation

Theorems

68-95-99.7 Rule (Empirical Rule)

Suitable Grade Level

College Statistics or Advanced High School