there are 1700 chairs in a school hall.40% of the chairs are blue and the rest are red. how many blue chairs must be added so that the number of red chairs will be decreased to 50%

there are 680 blue chairs
[tex] \frac{1700}{100} = \frac{x}{40} \\ x = \frac{1700 \times 40}{100} = \frac{68000}{100} = 680[/tex]
and 1,020 red chairs
[tex]1700 - 680 = 1020[/tex]
so we should add 340 blue chairs
[tex]1020 - 680 = 340[/tex]
and now we have the number of 2040 chairs in school. 50% blue and 50% red

good luck

Answer Link

Аноним Аноним · Answer 2 · 2018-04-04T11:01:40+02:00

--------------------------------------------------------------------------------
Number of blue chairs :
--------------------------------------------------------------------------------
Blue chairs= 40% of 1700 = 0.4 x 1700 = 680

--------------------------------------------------------------------------------
Number of red chairs :
--------------------------------------------------------------------------------
1700 - 680 = 1020

--------------------------------------------------------------------------------
Number of blue chairs to be added so that they are equal:
--------------------------------------------------------------------------------
1020 - 680 = 340

----------------------------------------
Chairs Now:
----------------------------------------
Red chairs = 1020
Blue chairs = 680 + 340 = 1020

---------------------------------------------------------------------------------------------------
Answer: We add 340 blue chairs so that both are 50% (or half) of the total chairs.
---------------------------------------------------------------------------------------------------