Use the given square-root value to evaluate a related root: If √15 = 3.88, compute the numerical value of √(5/3). Show the relationship that links these two quantities and give the result to two decimal places.

Aptitude Decimal Fraction Difficulty: Easy
Choose an option
  • A
    0.43
  • B
    1.89
  • C
    1.29
  • D
    1.63

Answer

Correct Answer: 1.29

Explanation

Introduction / Context:This question tests proportional reasoning with square roots. When a square root of a product is known (here √15), you can form related roots such as √(5/3) by using basic root properties. The goal is to connect √(5/3) to √15 cleanly and compute a decimal answer without a calculator-heavy approach.

Given Data / Assumptions:

  • Given: √15 = 3.88 (use this value as exact for the problem).
  • Find: √(5/3).
  • Standard property: √(a/b) = √a / √b for a, b > 0.

Concept / Approach:Rewrite 5/3 as 15/9 so that its square root links directly to √15. Since √(15/9) = √15 / √9 and √9 = 3, we obtain a simple division of the provided value 3.88 by 3. This avoids approximations beyond the given data and keeps the computation short and reliable.

Step-by-Step Solution:

Write 5/3 as 15/9.Use the identity: √(a/b) = √a / √b.So √(5/3) = √(15/9) = √15 / √9.Compute with given values: √15 / √9 = 3.88 / 3 = 1.293333… ≈ 1.29.

Verification / Alternative check:

Square 1.29 as a quick check: 1.29^2 ≈ 1.6641, which is close to 5/3 ≈ 1.6667. The tiny difference comes from the rounded given √15.

Why Other Options Are Wrong:

  • 0.43: Much too small; would imply √(5/3) < 1.
  • 1.63 and 1.89: Too large; they would correspond to squaring above the target 1.6667 baseline.

Common Pitfalls:

  • Forgetting to take √9 = 3 when converting 5/3 to 15/9.
  • Rounding too early; compute 3.88 / 3 first, then round.

Final Answer:

1.29
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