Overall height = (n₁a₁ + n₂a₂) / (n₁ + n₂)
n₁= 20,
a₁ = 5 ft 11 inches = 5 x 12 + 11 = 71 inches
n₂= 18,
a₂ = 6 ft 2 inches = 6 x 12 + 2 = 74 inches

Correct Option: A

Overall height = (n₁a₁ + n₂a₂) / (n₁ + n₂)
n₁= 20,
a₁ = 5 ft 11 inches = 5 x 12 + 11 = 71 inches
n₂= 18,
a₂ = 6 ft 2 inches = 6 x 12 + 2 = 74 inches

∴ Overall height = [(20) (71) + (18) (74)] / (20+18)
= (1420 + 1332) / 38 = 72.42 inches

∴ 7th result = (Sum of first seven result) + (Sum of last seven results) - (Sum of all the results)

Correct Option: D

According to the fundamental to the fundamental formula
Average(A)= Sum (S) / Number(N)

From the question 60 = S / 13
∴ S = 60 x 13 = 780

Sum of first seven result = 59 x 7 = 413
Sum of last seven result = 61 x 7 = 427

∴ 7th result = (Sum of first seven result) + (Sum of last seven results) - (Sum of all the results)
= (413 + 427 - 780 )
= (840 - 780)
= 60

NoteSum of first seven when added to the sum of last seven result, then repetition of 7th result takes place.

Here n₁ = 19, a₁ = 74, n₂ = 38, a₁ = 63
Total average weight = (n₁a₁ + n₂ a₂) / (n₁ + n₂)

Correct Option: D

Here n₁ = 19, a₁ = 74, n₂ = 38, a₁ = 63
Total average weight = (n₁a₁ + n₂ a₂) / (n₁ + n₂)
= [(19) (74) + (38) (63)] / (19 + 38)
= 3800/57 ≈ 67 kg

Here, n = 10, a = 60, b = 62
Number of runs scored in 11th inning
= n (b - a) + b

Correct Option: D

Here, n = 10, a = 60, b = 62
Number of runs scored in 11th inning
= n (b - a) + b
= 10 (62 - 60) + 62
= 20 + 62 = 82

Here n= 34, a = 42 and b = 42.4
Weight of the teacher.
= n(b -a) + b

Correct Option: B

Here n= 34, a = 42 and b = 42.4
Weight of the teacher.
= n(b -a) + b
= 34 ( 42.4 - 42) + 42.4
= 13.6 + 42.4 = 56.0 kg