Question

Q6 a number is increased by 20% and then it is
decreased by 20% find the next increase or decrease
percent​

Answer 1

Answer:

4%

Step-by-step explanation:

let original number be K

a number is increased by 20% and then it is

decreased by 20% = k (100+20/100) (100-20/100)

= k (120/100) (80/100)

= k (6/5) (4/5)

= k(24/25)

number decrease

decrease= difference= k- k(24/25)

= (25k-24k)/25

= k/25

decrease% = (decrease/original) 100 %

=( k/25)/k 100%

= 4%

decrease in% = 4%

Answer 2

Answer:

4%

Explanation :

Let's assume the number as $x$

Now,

It is increased by 20%

So,

$\to x + (20\% \: {\sf{of}}\: x)$

$\to x + \dfrac{x}{5}$

$\to \dfrac{6x}{5}$

And also, the resulting number decreases by 20%

So,

$\to \dfrac{6x}{5} - \big(20\% \:{\sf{of}}\: \dfrac{6x}{5}\big)$

$\to \dfrac{6x}{5} - \dfrac{6x}{25}$

$\to \dfrac{30x - 6x}{25}$

$\to \dfrac{24x}{25}$

Since,

$\to x > \dfrac{24x}{25}$

It is net decreased.

${\sf{Net \: decreased =}} \:x - \dfrac{24x}{25} = \dfrac{x}{25}$

$\sf \to {Decreased \% = \dfrac{Net \: decrease}{Original \: number}\times 100}$

${ \to \dfrac{\dfrac{x}{25}}{x} \times 100}$

$\to \sf 4\%$

Required answer : 4%