No. 1
Three eights of the class got sick. Three more students got sick, leaving only half the class at school. How many students were not sick?
(possible choice of answer: 8, 12, 16, 20)
No. 2
3/4 of a jar of lollies are multi-coloured and the rest are black. 6 of the black lollies are eaten and now there is 6/7 of the jar of multicoloured lollies. How many black lollies were in the jar at the start?
(possible answers: 6, 8, 10, 12)
Hi Rod,Quote:
Originally Posted by Rod
1. Let x = the total number of students
$\displaystyle \frac{3}{8}x$ = the number who initially got sick
So, $\displaystyle \frac{3}{8}$ of the total + 3 more = $\displaystyle \frac{1}{2}$ the class (x).
Equation: $\displaystyle \frac{3}{8}x+3=\frac{1}{2}x$
Solve the equation to find the total number of students (x)
$\displaystyle x = 24$
$\displaystyle \frac{3}{8}\left(24\right)=9$ initially sick
$\displaystyle 9+3=12$ total sick students
$\displaystyle 24-12=12$ = number of students not sick.
What is the difference between one-half and three-eighths? (Hint: Subtract.)Quote:
Originally Posted by Rod
This fraction represents the three additional students. How many students were there, in total? (Hint: Since "1" means "one whole student body", figure out what you'd have to multiply by to convert the fraction from above into "1", and then multiply "3" by this value.)
What is half of this number? (Hint: Divide by 2.)
This one works very much like the last one:Quote:
Originally Posted by Rod
If three-fourths were non-black, then one-fourth were black. If six-sevenths are now non-black, then one-seventh are now black.
What is the difference between one-fourth and one-seventh?
Since this fraction represents "six black", then what was the original number of black?
If you get stuck, please reply showing how far you have gotten. Thank you! :D
Thanks for your help!
In the land of the blind, the one eyed man is king, but he still only has one eye!Quote:
Originally Posted by masters
Lets say there are x students in classQuote:
Originally Posted by Rod
Initial case
No. of students who are sick = 3x/8
Second case
No. of students sick = x/2
According to question
3x/8 + 3 = x/2
---solve it
x = 24 , total no. of students healthy = x/2 = 12
-------------------------------------
Lets say initially x are there
Initial case
No. of colored = 3x/4
So no. of black = x/4
Second case
No. of black = x/4 - 6
No. of colored = 3x/4 (Unchanged)
But total no. this time = x-6
Hence Ratio is
$\displaystyle \frac{\frac{3x}{4}}{x-6} = \frac{6x}{7}$
----
$\displaystyle \frac{3}{4x-24} = \frac{6}{7} $
21 = 24x - 144
24x = 165
x= a fraction take this appx. value to the closest number , in other words do round-off
I hope I am not wrong (Thinking)
Can I rather solve by saying:
let x = number of coloured lollies and y = number of blacks
then the ratio 3/1 = x/y so x = 3y ........(1)
and y-6 = 6/7x ............................................ .(2)
substituting x = 3y in (2)
DOESN'T WORK!
