Directions: Study the table carefully and answer the given questions. Number of pages printed by 5 printers during 5 days | Printers $\rightarrow$
Days $\downarrow$ | A | B | C | D | E | | :--- | :--- | :--- | :--- | :--- | :--- | | Monday | 139 | 147 | 211 | 141 | 184 | | Tuesday | 141 | 189 | 164 | 189 | 151 | | Wednesday | 115 | 141 | 159 | 156 | 136 | | Thursday | 89 | 223 | 120 | 147 | 113 | | Friday | 187 | 93 | 257 | 160 | 124 | What is the average number of pages printed by printer B on Monday, Tuesday and Friday?

### Concept & Averages The average is calculated by summing all the relevant data points and dividing by the total number of points. $$ \text{Average} = \frac{\text{Sum of Observations}}{\text{Number of Observations}} $$ ### Step-by-Step Solution 1. **Extract data for printer B:** - Monday = $147$ - Tuesday = $189$ - Friday = $93$ 2. **Calculate the sum:** - $\text{Sum} = 147 + 189 + 93 = 429$ 3. **Calculate the average:** - Number of days = $3$ - $\text{Average} = \frac{429}{3} = 143$ ### Exam Strategy & Shortcut Assume a base average, say $140$. Find the deviations: Monday is $+7$, Tuesday is $+49$, Friday is $-47$. Sum of deviations = $7 + 49 - 47 = 9$. Divide the sum of deviations by $3$: $9 / 3 = 3$. Add this to the assumed average: $140 + 3 = 143$. This method avoids large additions. ### Common Pitfall Adding the values correctly but forgetting to divide by $3$, or miscounting the number of days specified. ### Final Answer Therefore, the correct answer is **143**.