Average temperature of first 4 days of a week is 6°C and that of the last 4 days is 40.3°C. If the average temperature of the week be 39.1°C, the temperature on 4th day is? Choose the correct choice.
A) 36.7 ° c  B) 38.6 ° c  C) 39.8 ° c  D) 41.9 ° c  E) 51.9 ° c

Rationale: let temperature on 4 th day be x ° c therefore , 4 x 38.6 + 4 x 40.3 - x = 7 x 39.1 = > x = 41.9 therefore , temperature on 4 th day = 41.9 ° c . answer : d
Answer: D