The average temperature of a city for the first four days of the week is 25°C, and the average temperature for the last four days is 30°C. If the average temperature for the entire week is 27°C, then what is the temperature on the fourth day?
- A29°C
- B31°C
- C30°C
- D28°C
Solution & Step-by-step Explanation
Total temperature for a week (7 days) = 7×27=189
∘
C
Sum of temperatures of first 4 days = 4×25=100
∘
C
Sum of temperatures of last 4 days = 4×30=120
∘
C
Sum of these 8 days includes the 4
th
day twice:
Sum=100+120=220
∘
C
Temperature on 4
th
day = 220−189=31
∘
C
∘
C
Sum of temperatures of first 4 days = 4×25=100
∘
C
Sum of temperatures of last 4 days = 4×30=120
∘
C
Sum of these 8 days includes the 4
th
day twice:
Sum=100+120=220
∘
C
Temperature on 4
th
day = 220−189=31
∘
C