There are 175 pupils in a hall. 40% of them are boys. 25 girls enter the hall. What percentage of the pupils in the hall now are boys?
Start off by figuring out 40% (percent means you take 40 and divide it by 100) of ("of" means multiply) 175.
So
(40/100) x 75 = ?
That will tell you how many boys there are now.
Next, figure out how many girls there are now. (How many are left over?)
Add 25 to the girls' number (since 25 girls just walked in). Add 25 to 175 people (since 25 people just walked in).
"New number of girls" divided by "new number of people" gives you the percentage. (It will be higher than 60%, just as a control of error).
To find out the percentage of boys in the hall after 25 girls enter, we need to calculate the total number of pupils first.
The number of boys in the hall is currently 40% of 175 pupils, so we multiply 175 by 0.4:
175 * 0.4 = 70
Adding 25 girls to the hall, the total number of pupils is now:
175 + 25 = 200
Now, we can calculate the percentage of boys in the hall by dividing the number of boys (70) by the total number of pupils (200) and multiplying by 100:
(70 / 200) * 100 = 35%
Therefore, after 25 girls enter the hall, 35% of the pupils in the hall are boys.
To find the new percentage of boys in the hall after 25 girls enter, you need to first calculate the number of boys before the girls entered and subtract the number of boys who left or entered.
First, find the initial number of boys in the hall:
40% of 175 pupils = (40/100) * 175 = 70 boys
Now, find the new number of boys after 25 girls enter the hall:
70 boys - 25 girls = 45 boys
To calculate the percentage of boys in the hall now, divide the number of boys by the new total number of pupils and multiply by 100:
(45 boys / 175 total pupils) * 100 = 25.71%
So, the new percentage of boys in the hall after 25 girls entered is approximately 25.71%.