Answer: Option C
Answer: (c)Let the second number be x. Then first number = $x/2$ and third number = 2x According to the question, $x/2$+x+2x=28×3⇒ ${x+2x+4x}/2$=28×3⇒ 7x = 28 × 3 × 2 ⇒ x = $168/7$ = 24 ∴ Third number = 2 × 24 = 48 Aliter : Using Rule 15,From three numbers, first number is 'a’ times of 2nd number, 2nd number is 'b’ times of 3rd number and the average of all three numbers is x, then, First number = $\text"3ab"/ \text"1+b+ab"$ x ; Second number = $\text"3b"/ \text"1+b+ab"$ x ; Third number = $\text"3b"/ \text"1+b+ab"$ x Here, a = $1/2$, b = $1/2$, x = 28 Third Number= $3/\text"1+b+ab"$ ×x = $3/{1+{1/2}+{1/2}×{1/2}}$×28= $3/{{4+2+1}/4}$×28= ${3×4×28}/7$= 48