Approximation Test-7 (Complete Revision)

Answer: Option C

Explanation

Given,

$\frac{5}{6}\times \frac{2}{9}÷\frac{4}{9}÷\frac{6}{7}=?$

It can aslo be approximated as

$$\begin{gathered} = \frac{5}{3}\times \frac{1}{9}\times \frac{9}{4}\times \frac{7}{6} \\ =\frac{{\displaystyle 5}}{{\displaystyle 3}}\times \frac{{\displaystyle 1}}{{\displaystyle 4}}\times \frac{{\displaystyle 7}}{{\displaystyle 6}} \\ =\frac{35}{72}= 0.48 \end{gathered}$$

= 0.48 ≈ 0.49

Hence, Option C is correct.

Answer: Option E

Explanation

Given,

${\text{95}}^{3.7}÷{95}^{0.99890}={95}^{?}$

It can also be written as

${\text{95}}^{3.7}÷{95}^{0.99890}={95}^{?}$

[Put ?=x]

$$\begin{gathered} = {95}^{3.7}÷{95}^{0.998}={95}^x \\ = {95}^{3.7-0.9989}={95}^x \\ = {95}^{2.7011}={95}^x \end{gathered}$$

(since the bases are the same,

set the exponents equal)

= x= 2.7011

=2.7011 ≈ 2.7

Hence, Option E is correct.

Answer: Option B

Explanation

Given, 

$\sqrt{1000}+\frac{3.001}{4.987}of1891.992=?$

It can also be approximated as

$\sqrt{1000}+\frac{3.000}{5.000}of1900=?$

$$\begin{gathered} = \sqrt{1000}+\frac{3}{5}\times 1900 \\ = \sqrt{1000}+3\times 380 \\ = 10\sqrt{10}+1140 \\ = 1171.6 \end{gathered}$$

=1171.6 ≈ 1230

Hence, Option B is correct.

Answer: Option C

Explanation

Given,

0.0004÷0.0001×36.000009=?

It can also be written as

0.0004÷0.0001×36.000000=?

= 4×36.000000

= 144 ≈ 145

Hence, Option C is correct.

Answer: Option C

Explanation

Given,

63.9872×9449.8780÷243.0034=(?)²

It can also be written as

64×9450÷243=(?)² 

= 64×39

= 2496 ≈ (?)²

[Put ?=x]

x= 50

= 2496 ≈ 2500

Hence, Option C is correct.