alleryWhich of the following is equivalent to the ratio $4 : 5$?
- $5 : 4$
- $8 : 10$
- $4 : 10$
- $5 : 8$
Show answer and solution
Correct answer: B. $8 : 10$
Multiplying both terms of a ratio by the same non-zero number preserves it: $4 : 5 = 8 : 10$.
RRB NTPC Ratio and Proportion — practice questions
Explore 6 free Ratio and Proportion questions in RRB NTPC Quantitative Reasoning. Open each question or exercise to read its content, reference answers and available explanation.
Practise Ratio and Proportion with Quill →Ratio and Proportion questions and exercises with answers
Showing questions 1–6 of 6.
Which of the following is equivalent to the ratio $4 : 5$?Read the answer and worked solution →Find the fourth proportional to $4$, $9$ and $12$.Read the answer and worked solution →Find the mean proportional between $16$ and $25$.Read the answer and worked solution →If $\dfrac{a}{b} = \dfrac{3}{5}$, find the value of $\dfrac{a+b}{a-b}$.Read the answer and worked solution →Find the compounded ratio of $(2 : 3)$, $(5 : 7)$ and $(4 : 9)$.Read the answer and worked solution →₹$5400$ is divided among A, B and C in the ratio $3 : 5 : 7$. How much does B receive?Read the answer and worked solution →
Worked practice questions
Find the fourth proportional to $4$, $9$ and $12$.
- $18$
- $21$
- $24$
- $27$
Show answer and solution
Correct answer: D. $27$
If $4 : 9 = 12 : x$, then by the product-of-means equals product-of-extremes rule, $4x = 9 \times 12 = 108$, so $x = 27$.
Find the mean proportional between $16$ and $25$.
- $18$
- $20$
- $22$
- $24$
Show answer and solution
Correct answer: B. $20$
Mean proportional $= \sqrt{a \times b} = \sqrt{16 \times 25} = \sqrt{400} = 20$.
Option A (18) is the arithmetic mean $(16+25)/2 \approx 20.5$ rounded down — close, but not the geometric mean asked for.
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