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RRB NTPC Mains or Stage 2 Model Paper 5 with solutions

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Question : 1 of 120

Marks: +1, -0

What is the value of

\sqrt{7.84} + \sqrt{0.0784} + \sqrt{0.000784} + \sqrt{0.00000784}

?

3.08
3.108
3.1008
3.1108

Solution:

Concept:

Find each square root by converting the decimals into fractions.

Explanation:

\sqrt{7.84} = \sqrt{\frac{784}{100}} = \frac{28}{10} = 2.8

\sqrt{0.0784} = \sqrt{\frac{784}{10000}} = \frac{28}{100} = 0.28

\sqrt{0.000784} = \sqrt{\frac{784}{1000000}} = \frac{28}{1000} = 0.028

\sqrt{0.00000784} = \sqrt{\frac{784}{100000000}} = \frac{28}{10000} = 0.0028

Now add all values:

2.8 + 0.28 + 0.028 + 0.0028 = 3.1108

Answer:

3.1108

, so option D is correct.

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