⇒ The total sum of 10 number = 10 × 26.5 = 265 ⇒ The total sum of first 6 number = 6 × 25 = 150 ⇒ The total sum of last 6 number = 6 × 29 = 174 ⇒ The total sum of first six number and last six number = 150 + 174 = 324 ⇒ The sum of 5th and 6th number = 324 - 265 = 59 ⇒ The average of 5th and 6th number = 59/2 = 29.5