In expressing a length of 81.472 km as nearly as possible with the three significant digits, find the percentage error

Answer: Option A

Explanation:

Let the number be x,
then,
$$\begin{aligned} \frac{5}{3} - \frac{3}{5} = \frac{16}{15}x \end{aligned}$$

Error% = $$\begin{aligned} (\frac{16}{15}x * \frac{3}{5} * 100)% = 64% \end{aligned}$$

Answer: Option C

Explanation:

Let the third number is x.
then first number = (100-30)% of x
= 70% of x = 7x/10

Second number is (63x/100)

Difference = 7x/10 - 63x/100 = 7x/10

So required percentage is, difference is what percent of first number

=> (7x/100 * 10/7x * 100 )% = 10%

Answer: Option B

Explanation:

Question of this type looks a bit typical, but it is too simple, as below...

It will be 8 * 20/100 = 1.6

Answer: Option A

Explanation:

1/2/1/3 * 100 = 1/2 * 3/1 * 100 = 150 %

Answer: Option C