The bar graph below shows the monthly demand and production figures (in units) of five T.V. companies, A, B, C, D and E. Study it and answer the question that follows. What is the difference between the average demand and the average production of the five companies taken together?
Show Hint
Add all five demand values and all five production values separately, then compare the two averages.
Step 1: Find the demand minus production gap for each company separately. A: $3000 - 1500 = 1500$. B: $600 - 1800 = -1200$. C: $2500 - 1000 = 1500$. D: $1200 - 2700 = -1500$. E: $3300 - 2200 = 1100$.
Step 2: Add up all five gaps. Sum of gaps $= 1500 + (-1200) + 1500 + (-1500) + 1100 = 1400$.
Step 3: Divide the total gap by the number of companies. Since the average of a set of differences equals the difference of the two averages, dividing $1400$ by $5$ gives the answer straight away: $\dfrac{1400}{5} = 280$.
Final Answer: Working company by company gives the same result without adding all demand and all production values separately first. \[ \boxed{280} \]
