Correct way of finding Sum of Ratios This is more of a statistical question rather than Excel Related. In the attached image, im trying to find out the ratio of Profit/Sales and then calculating overall Profit/Sales
Please let me know which one is correct.
 A: In the first method you're equal weighting each time period. In the second method, you're weighting by sales.
Let $p_t$ be profit in period $t$. Let $s_t$ be sales in period $t$. Let $y_t =\frac{p_t}{s_t}$ be profit to sales in period $t$.
First method:
Your first method of calculation is to take the sample mean of $y_t$.
$$ \bar{y}^{(1)} = \frac{1}{T}\sum_{t=1}^T y_t $$
Since $T=5$, every observation gets weight $\frac{1}{5}$. You're equal weighting each period.
Second method:
The second method is:
\begin{align*}
\bar{y}^{(2)} &= \frac{\sum_t p_t}{\sum_t s_t} \\
&= \frac{\sum_t s_t y_t}{\sum_t s_t}\quad \quad \text{since } y_t = \frac{p_t}{s_t}\\
&= \sum_t \left( \frac{s_t}{\sum_t s_t} \right) y_t
\end{align*}
In summary, your second method is equivalent to:
$$\bar{y}^{(2)} = \sum_{t=1}^T w_t y_t\quad \quad w_t = \frac{s_t}{\sum_{t=1}^T s_t}$$
Instead of equally weighting each time period (i.e. $\frac{1}{T}$), you're taking the average of the profit to sales ratio $y_t$ where you weight each period $t$ by sales. 
Which makes more sense?
That's going to depend a lot more on context. If $t$ represents a month and you're thinking about overall, annual profitability, then method 2 is going to be more robust against all kinds of time series issues. 
Imagine I'm a ski resort. Basically all my sales occur in Dec, Jan, and Feb. Taking the average where I give December the same weight as September is going to be VERY different than taking the average where I weight Dec 20x as much as September because December has 20x the sales.
