2/3 of all the people who attended a certain party arrived by 8:00 PM. How many people arrived by 8:00 PM?

(1) 9 people arrived after 9:00 PM.

(2) 21 people arrived between 8:00 PM and 9:00 PM, and by 9:00 PM 90% of all the people who attended the party had arrived.

a) How many people who attended a certain party arrived by 8 PM 60 people

Step-by-step explanation:

2/3 of all people who attended a certain party arrived by 8 P. M. That means that 1/3 arrived in other time. But 2/3 + 1/3 is total number of people in the party.

1) 9 people arrived after 9 PM

And in 2

2) ... By 9.00 PM 90 % of people were already in the party and. That means

that 9 people who arrived after are 10 %

Then if 9 people are 10 %

x people are 100%

x = (100*9) / 10 ⇒ x = 900/10

x = 90

Here we got total number of people in the party 90

Then 2/3 of 90 is 180/3 60

1/3 0f 90 is 30