My Math Forum How does the text book come to its answer

 Algebra Pre-Algebra and Basic Algebra Math Forum

March 22nd, 2013, 09:52 AM   #1
Newbie

Joined: Mar 2013

Posts: 4
Thanks: 0

How does the text book come to its answer

Hi, I am trying to understand how they get 162.5mm as the answer. When I put this into the highlighted formula, I do not end up with 25? I am trying to get R on its own.

Luke
Attached Images
 picture.png (110.8 KB, 178 views)

March 22nd, 2013, 10:20 AM   #2
Math Team

Joined: Oct 2011

Posts: 14,343
Thanks: 1024

Re: How does the text book come to its answer

Quote:
 Originally Posted by luke93 Hi, I am trying to understand how they get 162.5mm as the answer.
Given data is in m ; the 162.5 is in mm ; so doing the math should give .1625

I calculated it; ended up with SQRT(.6336 / 24) = ~.16248

.16248 / 1000 = 162.5 (rounded)

Ya'll ok now?

 March 22nd, 2013, 10:30 AM #3 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,932 Thanks: 1127 Math Focus: Elementary mathematics and beyond Re: How does the text book come to its answer $25\,=\,\frac{r^2\,-\,0.0064}{r^2\,-\,0.0256} \\ 25r^2\,-\,25(0.0256)\,=\,r^2\,-\,0.0064 \\ 24r^2\,=\,-0.0064\,+\,25(0.0256) \\ r^2\,=\,\frac{0.6336}{24} \\ r\,=\,\sqrt{0.0264}\,\approx\,0.1625$
 March 22nd, 2013, 11:07 AM #4 Newbie   Joined: Mar 2013 Posts: 4 Thanks: 0 Re: How does the text book come to its answer Thank you both for the replies, it all makes sense now
March 22nd, 2013, 04:13 PM   #5
Global Moderator

Joined: Dec 2006

Posts: 20,484
Thanks: 2041

Quote:
 Originally Posted by Denis .16248 / 1000 = 162.5 (rounded) Ya'll ok now?
.16248 * 1000 ... okay?

March 22nd, 2013, 04:25 PM   #6
Math Team

Joined: Oct 2011

Posts: 14,343
Thanks: 1024

Re:

Quote:
Originally Posted by skipjack
Quote:
 Originally Posted by Denis .16248 / 1000 = 162.5 (rounded) Ya'll ok now?
.16248 * 1000 ... okay?
Aye, aye, Skipper! (first mistake this year )!

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post sleipnir234 Advanced Statistics 2 February 3rd, 2014 03:46 PM roberto.salamanca Algebra 8 January 31st, 2014 10:45 AM dennisdixon Algebra 5 June 20th, 2013 11:53 PM RealMadrid Algebra 4 February 11th, 2013 06:31 AM roberto.salamanca New Users 8 December 31st, 1969 04:00 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top