## Q&A - P5 Math

YellowBelt
Posts: 17
Joined: Thu Jul 09,

### Re: Q&A - P5 Math

Thanks. Any idea on using the percentage method?

garlicmummy
OrangeBelt
Posts: 33
Joined: Sun Nov 22,

### Re: Q&A - P5 Math

DaddyD wrote:Thanks. Any idea on using the percentage method?
It's similar actually. But i will break it down further:

1st week
Total – 100%

2nd week
percentage increase 40/100 x 35% = 14%
Total - 35 + 14 = 49%

percentage decrease 5/100 x 65% = 3.25%
Total - 65 – 3.25 = 61.75%

Total % cookies baked in week 2 - 49 + 61.75 = 110.75%

Diff – 110.75% – 100% =10.75%

10.75% – 43
1% – 4
49% – 49 x 4 = 196 (Chocolate cookies)

ksraja69
GreenBelt
Posts: 132
Joined: Fri Dec 18,

### A Mathlympics Question

4 men and 4 women are to be seated at round table for dinner.If the men and women take alternate seats, how many arrangements are possible?

S_Mummy
GreenBelt
Posts: 137
Joined: Tue Dec 15,

### Re: Q&A - P5 Math

Johan had some \$5 notes and \$2 notes. The ratio of the number of \$5 notes to the number of \$2 notes was 6 : 11. When he exchanged 10 pieces of \$5 notes for some \$2 notes, the ratio of the number of \$5 notes to the number of \$2 notes became 2 : 7. How much money did Johan have altogether?

Ender
BrownBelt
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### Re: A Mathlympics Question

ksraja69 wrote:4 men and 4 women are to be seated at round table for dinner.If the men and women take alternate seats, how many arrangements are possible?

Nebbermind
KiasuGrandMaster
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### Re: Q&A - P5 Math

Johan had some \$5 notes and \$2 notes. The ratio of the number of \$5 notes to the number of \$2 notes was 6 : 11. When he exchanged 10 pieces of \$5 notes for some \$2 notes, the ratio of the number of \$5 notes to the number of \$2 notes became 2 : 7. How much money did Johan have altogether?
Before

No. of \$5 = 6U
No. of \$2 = 11U

After

(1) No. of \$5 = 6U - 10 = 2P
(2) No. of \$2 = 11U + 25 = 7P (10 * \$5 can exchange for 25 * \$2)

From (1), P = 3U - 5

Substitute 7P or 7*(3U - 5) into (2) and you can find U.

From there you can total up the \$5 (6U) and \$2 (11U)

Ender
BrownBelt
Posts: 727
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### Re: Q&A - P5 Math

Johan had some \$5 notes and \$2 notes. The ratio of the number of \$5 notes to the number of \$2 notes was 6 : 11. When he exchanged 10 pieces of \$5 notes for some \$2 notes, the ratio of the number of \$5 notes to the number of \$2 notes became 2 : 7. How much money did Johan have altogether?
First we find out how many pieces of \$2 notes he gains, when he exchange for 10 pieces of \$5.
10 x \$5 = \$50
Number of \$2 =50/2= 25 pieces

6u -10 = 2p ---------> 42u-70 = 14p
11u+25 = 7p -------->22u+50 = 14p

42u - 70 = 22u + 50
20u = 120
u = 6

\$5 notes =>6u => 36pcs, value = \$180
\$2 notes =>11u => 66pcs, value = \$132

Total = \$312

EconsPhDTutor
OrangeBelt
Posts: 39
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### Re: A Mathlympics Question

ksraja69 wrote:4 men and 4 women are to be seated at round table for dinner.If the men and women take alternate seats, how many arrangements are possible?
Fix any man in place (call him Man #1). To his left is a woman (4 possible choices) --- call her Woman #1. To her left is a man (3 possible choices) --- call him Man #2. To his left is a woman (3 possible choices) --- call her Woman #2. Etc.

Altogether, there are 4 × 3 × 3 × 2 × 2 × 1 × 1 = 144 possible arrangements.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

www.EconsPhDTutor.com

S_Mummy
GreenBelt
Posts: 137
Joined: Tue Dec 15,

### Re: Q&A - P5 Math

Thank you very much, Ender & Nebbermind

S_Mummy
GreenBelt
Posts: 137
Joined: Tue Dec 15,