1. **Problem Statement:** We are given two sets of returns: individual security returns $R_i$ and market returns $R_m$. We need to compute the alpha ($\alpha$) and beta ($\beta$) of the security.
2. **Formulas:**
- Beta ($\beta$) measures the sensitivity of the security's returns to the market returns and is given by:
$$\beta = \frac{\text{Cov}(R_i, R_m)}{\text{Var}(R_m)}$$
- Alpha ($\alpha$) is the intercept of the security's return regression on the market return and is given by:
$$\alpha = \bar{R_i} - \beta \bar{R_m}$$
where $\bar{R_i}$ and $\bar{R_m}$ are the means of $R_i$ and $R_m$ respectively.
3. **Calculate means:**
$$\bar{R_i} = \frac{14 + 18 + 6 + 12 + 13 + 14 + 11 + 6 + 9 + 8}{10} = \frac{111}{10} = 11.1$$
$$\bar{R_m} = \frac{16 + 20 + 9 + 8 + 10 + 9 + 11 + 18 + 17 + 15}{10} = \frac{133}{10} = 13.3$$
4. **Calculate covariance $\text{Cov}(R_i, R_m)$:**
$$\text{Cov}(R_i, R_m) = \frac{1}{n} \sum_{k=1}^{n} (R_{i,k} - \bar{R_i})(R_{m,k} - \bar{R_m})$$
Calculate each term:
- $(14 - 11.1)(16 - 13.3) = 2.9 \times 2.7 = 7.83$
- $(18 - 11.1)(20 - 13.3) = 6.9 \times 6.7 = 46.23$
- $(6 - 11.1)(9 - 13.3) = -5.1 \times -4.3 = 21.93$
- $(12 - 11.1)(8 - 13.3) = 0.9 \times -5.3 = -4.77$
- $(13 - 11.1)(10 - 13.3) = 1.9 \times -3.3 = -6.27$
- $(14 - 11.1)(9 - 13.3) = 2.9 \times -4.3 = -12.47$
- $(11 - 11.1)(11 - 13.3) = -0.1 \times -2.3 = 0.23$
- $(6 - 11.1)(18 - 13.3) = -5.1 \times 4.7 = -23.97$
- $(9 - 11.1)(17 - 13.3) = -2.1 \times 3.7 = -7.77$
- $(8 - 11.1)(15 - 13.3) = -3.1 \times 1.7 = -5.27$
Sum: $7.83 + 46.23 + 21.93 - 4.77 - 6.27 - 12.47 + 0.23 - 23.97 - 7.77 - 5.27 = 15.67$
Divide by $n=10$:
$$\text{Cov}(R_i, R_m) = \frac{15.67}{10} = 1.567$$
5. **Calculate variance $\text{Var}(R_m)$:**
$$\text{Var}(R_m) = \frac{1}{n} \sum_{k=1}^n (R_{m,k} - \bar{R_m})^2$$
Calculate each term:
- $(16 - 13.3)^2 = 2.7^2 = 7.29$
- $(20 - 13.3)^2 = 6.7^2 = 44.89$
- $(9 - 13.3)^2 = (-4.3)^2 = 18.49$
- $(8 - 13.3)^2 = (-5.3)^2 = 28.09$
- $(10 - 13.3)^2 = (-3.3)^2 = 10.89$
- $(9 - 13.3)^2 = 18.49$
- $(11 - 13.3)^2 = (-2.3)^2 = 5.29$
- $(18 - 13.3)^2 = 4.7^2 = 22.09$
- $(17 - 13.3)^2 = 3.7^2 = 13.69$
- $(15 - 13.3)^2 = 1.7^2 = 2.89$
Sum: $7.29 + 44.89 + 18.49 + 28.09 + 10.89 + 18.49 + 5.29 + 22.09 + 13.69 + 2.89 = 171.10$
Divide by $n=10$:
$$\text{Var}(R_m) = \frac{171.10}{10} = 17.11$$
6. **Calculate beta ($\beta$):**
$$\beta = \frac{1.567}{17.11} \approx 0.0916$$
7. **Calculate alpha ($\alpha$):**
$$\alpha = 11.1 - 0.0916 \times 13.3 = 11.1 - 1.217 = 9.883$$
**Final answers:**
$$\boxed{\beta \approx 0.092, \quad \alpha \approx 9.88}$$
Alpha Beta F59921
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