Thursday, November 26, 2009

a.) The question is asking for how many hours St. John's is ahead of Brandon and to get the answer you have to find the difference of the time in St. John's and Brandon. In other much simpler words, you have to subtract it.
So the time in St. John's is -3 1/2 and the time in Brandon is -6, you have to subtract those two:
-3 1/2 - (-6) = -3 1/2 + 6/1

* now here comes the explaining part:
Why did it turn into a plus sign and where did the negative sign from the -6 go? and why is it 6/1 when it is only 6?

It turned into a plus sign and the negative sign from the 6 disappeared because it is now a positive number. When you have a question like this: a - (-b)=c, it is an "oopsie". I think it turns into a positive automatically because the question really is saying: a - 1 (-b)=c. So if you substitute those letters with numbers it will be like this:

-3 1/2 - (-6) = -3 1/2 -1 (-6)...... because of BEDMAS (order of operations) you have to get rid of the brackets first so you have to do -1 times -6 so it turns into +6.
Then it is 6/1 because mathematicians are lazy, they wrote 6 instead of 6/1 because they know that 6 and 6/1 are the same. It is just like the whole "oppsies" thing.

Now to solve it: - WOW that was a very long explanation -___- sorry guys.
-3 1/2 - (-6) = -3 1/2 + 6/1
= -7/2 + 12/2 (I just turned into an improper fraction because it is easier for me)
= 5/2 or 2 1/2 hours
St. John's is ahead of Brandon by 2 1/2 hours.

b.) The question is practically saying how many hours do you need to add to -8 to get to 5 1/2.
Here's a number line to make it easier (:

There's 13 1/2 hours.

c.) This question is asking for the difference of the time in Tokyo and Kathmandu. So all you have to do is subtract it.
9 - (5 3/4) = 9/1 - (23/4)
= 36/4 - 23/4 (equivalent fractions. Least common denominator because it needs the same denominators)
= 13/4 or 3 1/4 hours
There's 3 1/4 hours time difference between Tokyo and Kathmandu.

d.) This question is also asking for the difference of the time in Chatam Islands and St. John's. You also have to subtract.
12 3/4 - (-3 1/2) = 51/4 + 7/2 ( if you're asking about this equation again look up to the first one, the very long explanation )
= 51/4 + 14/4
= 65/4 or 16 1/4 hours
There's 16 1/4 hours time difference between Chatam Islands and St. John's.

e.) The question is asking you what location has the same time as the difference of Istanbul and Alice Springs halfway. It is asking you to subtract The time in Istanbul, +2, from the time in Alice Springs, +9 1/2 then divide in to t2 because it says "halfway" then see what other location in the list has the same number.
(9 1/2 + 2) ÷2 = (19/2 + 2/1) ÷2
= (19/2 + 4/2) ÷2
= 23/2 ÷ 2/1
= 23/2 x 1/2 ( you have to multiply the dividend by the divisors reciprocal)
= 23/4 or 5 3/4 hours
Kathmandu, Nepal has the same time so Kathmandu, Nepal is the location that has the same time as the difference of Istanbul and Alice Springs halfway.

Sorry if I didn't explain it that well. I tried to explain it and make it as detailed as possible. I guess I just made it long and broing -___-. At least I tried and finished my work ! :D

Mr. B. said...

Karen I really liked how you used the number line for question B. It really explains the question well. Thanks.

shaneille 9-05 said...

Great Job Karen! I really liked how you put in explanions on what you did, but i found a mistake when you have 2 negatives -(-) as harbeck says an UH OH not an *oopsie* just kidding, call it whatever you want. ! Anyways great job.

linda 9-05 said...

Hi Karen! Nice post! I suggest using more pictures to explain what you're doing because most teenagers learn better hands-on and with pictures. If we can see what you're doing it's easier for us all to learn. It's just a thought because when I was reading your post I often had to pause and picture what you were doing so I wouldn't get lost. Great work!