# Decimal Places

• Apr 1st 2008, 10:26 AM
SARAHL
Decimal Places
A Homework Question That We Are Struggling With - Any Answers??
1. Use The Clues To Find The Length Of Each Throw. Each Throw Is A Four Digit Number Of Metres.
Part One
*. The Tens Digit Is The Same As The Hundreths Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Units Digit Is Four Less Than The Tens Digit.
*. The Sum Of The Digits Is 20.
Part Two
*. The Tens Digit Is Twice The Units Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Hundreths Digit Is Half The Tenths Digit.

Find Another Possible Length To Fit These Clues.

00.00 Can Anyine Fill In The Blanks Please!!! ??.??
• Apr 1st 2008, 11:07 AM
earboth
Quote:

Originally Posted by SARAHL
A Homework Question That We Are Struggling With - Any Answers??
1. Use The Clues To Find The Length Of Each Throw. Each Throw Is A Four Digit Number Of Metres.
Part One
*. The Tens Digit Is The Same As The Hundreths Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Units Digit Is Four Less Than The Tens Digit.
*. The Sum Of The Digits Is 20.
....

Let the number be: ab.cd with $\displaystyle b, c, d \in \{0, 1, 2, ..., 9\}$ and $\displaystyle a \in \{1, 2, ..., 9\}$

From the wording of the problem you know:

$\displaystyle \left|\begin{array}{l}a = d\\b = c\\a = b+4\\a+b+c+d = 20\end{array}\right.$

Solve this system of simultaneous equations.

I've got the number 73.37
• Apr 1st 2008, 11:11 AM
Simplicity
Quote:

Originally Posted by SARAHL
A Homework Question That We Are Struggling With - Any Answers??
1. Use The Clues To Find The Length Of Each Throw. Each Throw Is A Four Digit Number Of Metres.
Part One
*. The Tens Digit Is The Same As The Hundreths Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Units Digit Is Four Less Than The Tens Digit.
*. The Sum Of The Digits Is 20.
Part Two
*. The Tens Digit Is Twice The Units Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Hundreths Digit Is Half The Tenths Digit.

Find Another Possible Length To Fit These Clues.

00.00 Can Anyine Fill In The Blanks Please!!! ??.??

I did this by algebra.

1.)
$\displaystyle 20 = 2x + 2(x-4)$
$\displaystyle 10 = x + x -4$
$\displaystyle 10 = 2x - 4$
$\displaystyle 14 = 2x$
$\displaystyle x = 7$

So, the throw is $\displaystyle 73.37m$.

2.)
$\displaystyle 84.42m$
• Apr 1st 2008, 11:15 AM
Jhevon
Quote:

Originally Posted by SARAHL
A Homework Question That We Are Struggling With - Any Answers??
1. Use The Clues To Find The Length Of Each Throw. Each Throw Is A Four Digit Number Of Metres.
Part One
*. The Tens Digit Is The Same As The Hundreths Digit.
*. The Units Digit Is The Same As The Tenths Digit.
*. The Units Digit Is Four Less Than The Tens Digit.
*. The Sum Of The Digits Is 20.

ok, so we are looking for a number of the form $\displaystyle xy.yx$ where $\displaystyle 0 \le x,y \le 9$

what clues do we have?

well, the $\displaystyle y = x - 4$ we are told, so that is one equation to work with.

we are also told that the sum of the digits is 20, so $\displaystyle x + x + y + y = 20$ is another equation we have to work with.

solve this system simultaneously.

try following the clues similarly for the second one

EDIT: wow, i was really late with this
• Apr 1st 2008, 02:12 PM
SARAHL
Thank you
(Hi)(Giggle)thank you for your help - I feel very stupid not being able to work it out!!! Thanks again!!