Of three numbers, the first is 4 times the second and 3 times the third. If the average of all the three numbers is 95, what is the third number ?
Options:
A .  130
B .  57
C .  76
D .  60
Answer: Option D Answer: (d)Let the third number be x, ∴ First number = 3x ∴ Second number = ${3x}/4$ According to the question, 3x + ${3x}/4$ + x = 3 × 95 ⇒ ${12x+3x+4x}/4$ = 285⇒ 19x = 285 × 4 ⇒ x = ${285×4}/19$ = 60 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 = 4, b = $3/4$, x = 95 Third Number = $3/\text"1+b+ab"$ ×x = $3/{1+{3/4}+4×{3/4}}$×95= ${3×4}/{4+3+12}$×95 = 60
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