Expected Return
1. **State the problem:**
Calculate the expected return and standard deviation of a population given the returns: 9.6%, -15.4%, 26.7%, -0.2%, 20.9%, 28.3%, -5.9%, 3.3%, 12.2%, 10.5%.
2. **Convert percentages to decimals:**
$$0.096, -0.154, 0.267, -0.002, 0.209, 0.283, -0.059, 0.033, 0.122, 0.105$$
3. **Calculate the Expected Return (mean) $\mu$:**
$$\mu = \frac{1}{n} \sum_{i=1}^n x_i = \frac{0.096 - 0.154 + 0.267 - 0.002 + 0.209 + 0.283 - 0.059 + 0.033 + 0.122 + 0.105}{10}$$
Calculate sum:
$$0.096 - 0.154 = -0.058$$
$$-0.058 + 0.267 = 0.209$$
$$0.209 - 0.002 = 0.207$$
$$0.207 + 0.209 = 0.416$$
$$0.416 + 0.283 = 0.699$$
$$0.699 - 0.059 = 0.640$$
$$0.640 + 0.033 = 0.673$$
$$0.673 + 0.122 = 0.795$$
$$0.795 + 0.105 = 0.900$$
So,
$$\mu = \frac{0.900}{10} = 0.09$$
Expected return is $9.0\%$.
4. **Calculate the population variance $\sigma^2$:**
$$\sigma^2 = \frac{1}{n} \sum_{i=1}^n (x_i - \mu)^2$$
Find each squared difference:
$$(0.096 - 0.09)^2 = 0.000036$$
$$(-0.154 - 0.09)^2 = (-0.244)^2 = 0.059536$$
$$(0.267 - 0.09)^2 = 0.177^2 = 0.031329$$
$$(-0.002 - 0.09)^2 = (-0.092)^2 = 0.008464$$
$$(0.209 - 0.09)^2 = 0.119^2 = 0.014161$$
$$(0.283 - 0.09)^2 = 0.193^2 = 0.037249$$
$$(-0.059 - 0.09)^2 = (-0.149)^2 = 0.022201$$
$$(0.033 - 0.09)^2 = (-0.057)^2 = 0.003249$$
$$(0.122 - 0.09)^2 = 0.032^2 = 0.001024$$
$$(0.105 - 0.09)^2 = 0.015^2 = 0.000225$$
Sum of squared differences:
$$0.000036 + 0.059536 + 0.031329 + 0.008464 + 0.014161 + 0.037249 + 0.022201 + 0.003249 + 0.001024 + 0.000225 = 0.177474$$
So,
$$\sigma^2 = \frac{0.177474}{10} = 0.0177474$$
5. **Calculate the Standard Deviation $\sigma$:**
$$\sigma = \sqrt{0.0177474} \approx 0.1332$$
6. **Conclusion:**
The expected return is $9.0\%$ and the population standard deviation is approximately $13.32\%$.