wooow.. thxz.. how about tis question?

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- Jun 23rd 2006, 10:30 AMxiaoz
wooow.. thxz.. how about tis question?

- Jun 23rd 2006, 11:06 AMJameson
(a)Start with the students who scored from 0-50 marks, inclusive. "x students scored less than 51 marks". So x students represents all the marks from 0-50. Now go to the students who made from 50-100 marks, inclusive. "2x students scored more than 49 marks". So 2x students represents all the marks from 50-100. We've counted the number of students who have scored 50 marks twice though, so we need to make note of the info the problem gave and subtract out one of these times we double counted.

So total number of students: $\displaystyle x+(2x-6)$

And we also know that the total number of students is: $\displaystyle 16$

$\displaystyle x+2x-6=18$

$\displaystyle x=\frac{24}{3}=8$ - Jun 23rd 2006, 01:52 PMQuickQuote:

Originally Posted by**some boring school assignment**

Now you need to find out how much more money you have, $\displaystyle 14400-12000=2400$

Now to find the percent increase, you need to divide the amount of money gained by the amount you started out with$\displaystyle 2400\div12000=0.2$ which equals 20%

Quote:

Originally Posted by**some boring school assignment**

$\displaystyle \text{Peter's Age 4 Years Ago}=$$\displaystyle \text{Peter's Age}-4\rightarrow P=6-4\rightarrow P=2 $

$\displaystyle \text{Mary's Age 4 Years Ago}=$$\displaystyle \text{Mary's Age}-4\rightarrow M=12-4\rightarrow M=8 $

Now we must find how much mary would have gotten, which means we have to divide Mary's age by peter's and Mary's ages added together

$\displaystyle \frac{M}{M+P}=\frac{8}{8+2}=\frac{8}{10}=0.8$

Now we multiply 12000 by 0.8 to get Mary's share

$\displaystyle 12000 \times 0.8 = 9600 $

So mary was right, her share didn't change. - Jun 23rd 2006, 02:19 PMSoroban
Hello, xiaoz!

I did part (ii) differently . . . same punchline.

Quote:

Mr. Wang decided to give his grandchildren, Peter and Mary, $12,000.

This sum is to be divided between them in the ratio of their ages.

The children's mother suggested that the money should be invested

to allow it to grow for a few years before being shared out.

After 4 years, Peter, aged 6, received his share of $4,800 and Mary, aged 12, received $9600.

(ii) Mary said, "There is no growth in my share at all." .Do you agree with Mary?

Four years ago, Peter was $\displaystyle 2$ years old and Mary was $\displaystyle 8$.

The ratio of their ages is: $\displaystyle 2:8 = 1:4$.

The $\displaystyle \$12,000$ would have been divided in the ratio: $\displaystyle \frac{1}{5} : \frac{4}{5}$

Peter would have received: $\displaystyle \frac{1}{5}\times\$12,000 \,=\,\$2,400$

Mary would have received: $\displaystyle \frac{4}{5}\times\$12,000 \,=\,\boxed{\$9,600}$

Four years later, the money has grown to $\displaystyle \$4,800 + 9,600 \,= \,\$14,400.$

Peter is $\displaystyle 6$ years old and Mary is $\displaystyle 12$.

The ratio of their ages is: $\displaystyle 6:12 = 1:2$

The $\displaystyle \$14,400$ is divided in the ratio: $\displaystyle \frac{1}{3}:\frac{2}{3}$

Peter received: $\displaystyle \frac{1}{3} \times \$14,400\,=\,\$4,800$

Mary received: $\displaystyle \frac{2}{3} \times \$14,400\,=\,\boxed{\$9,600}$

I agree . . . Mary's share did not increase.

- Jun 24th 2006, 06:58 AMxiaoz
nono.. (b)ii the ans is yes. had the money been shared 4 yrs ago. Mary would have recevied $12000x 8/16.... $9600~~???

- Jun 24th 2006, 07:33 AMQuickQuote:

Originally Posted by**xiaoz**

Quote:

Originally Posted by**Quick**

Quote:

Originally Posted by**Soroban**