The average temperature on Monday, Tuesday and Wednesday is 40° C. Tuesday, Wednesday and Thursday have an average temperature of 41° C. If Thursday's temperature was 42° C, what was the temperature on Monday?

Option 2 : 39° C

**Given:**

The average temperature on Monday, Tuesday and Wednesday = 40° C

The average temperature on Tuesday, Wednesday and Thursday = 41° C

The temperature on Thursday = 42° C

**Formula used:**

Average = Sum of all observations/Number of observation

**Calculation:**

The sum of temperature

⇒ Monday + Tuesday + Wednesday = 40 × 3 = 120° C ----(1)

The sum of temperature

⇒ Tuesday + Wednesday + Thursday = 41 × 3 = 123° C ----(2)

Thursday = 42° C put value in the above equation 2

⇒ Tuesday + Wednesday + 42° C = 123° C

⇒ Tuesday + Wednesday = 81° C ----(3)

Put value from equation 3 to equation 1

⇒ Monday + 81° C = 120° C

⇒ Monday = 39° C

**∴ The temperature on Monday was 39° C.**