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#Post#: 10970--------------------------------------------------
Math Problem Stumps British Students
By: Kerry Date: June 9, 2015, 6:34 am
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I don't see what's so hard about the problem; but here it is
from the story in the Daily News
HTML http://www.nydailynews.com/news/world/tricky-math-problem-viral-stumping-students-article-1.2248131:
"There are n sweets in a bag. Six of the sweets are orange. The
rest of the sweets are yellow. Hannah takes a random sweet from
the bag. She eats the sweet. Hannah then takes at random another
sweet from the bag. She eats the sweet. The probability that
Hannah eats two orange sweets is 1/3. Show that n²-n-90=0."
Students found it so difficult they took to Twitter to complain!
Puzzled pupils scratched their heads during test time, and then
unleashed their grievances on Twitter.
They also apparently started an online petition to get the
Edexcel exam board to let them retake the test or lower their
grade standards.
It has garnered more than 27,000 signatures.
Perhaps they need better teachers . . . or less Twitter time?
#Post#: 10972--------------------------------------------------
Re: Math Problem Stumps British Students
By: HOLLAND Date: June 9, 2015, 7:24 am
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I don't figure the answer either!! ;D
#Post#: 10973--------------------------------------------------
Re: Math Problem Stumps British Students
By: Kerry Date: June 9, 2015, 8:19 am
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[quote author=HOLLAND link=topic=1023.msg10972#msg10972
date=1433852659]
I don't figure the answer either!! ;D
[/quote]
There are n candies, so the odds of picking an orange one the
first time is 6/n. The odds for picking an orange one the
second time is 5/(n-1). So the odds of those two occurring
together is gotten by multiplying them and we know that is 1/3.
You get 30/(n[sup]2[/sup]-n) = 1/3. Thus 90 = n[sup]2[/sup]-n.
Or n[sup]2[/sup]-n-90 = 0.
I thought the question was going to be how many candies there
were; but they could have worked that out by trial or error.
There would have been 10.
6/10 x 5/9 =1/3
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Here's a logic problem from Singapore, also courtesy of the
Daily News
HTML http://www.nydailynews.com/new-york/education/cheryl-birthday-tricky-math-problem-viral-article-1.2183439.
Albert and Bernard just became friends with Cheryl, and they
want to know when her birthday is. Cheryl gives them a list of
10 possible dates.
May 15, May 16, May 19
June 17, June 18
July 14, July 16
August 14, August 15, August 17
Cheryl then tells Albert and Bernard separately the month and
the day of her birthday respectively.
Albert: I do not know when Cheryl’s birthday is, but I know that
Bernard does not know too.
Bernard: At first I don’t know when Cheryl’s birthday is, but I
know now.
Albert: Then I also know when Cheryl’s birthday is.
So when is Cheryl’s birthday?
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