Q&A - P3 Math

[rocklee]

Dear all Maths Experts out there,


Below are two P4 questions extracted from one of the 2010 Top scchool exam papers:

Q1. At a party, every girl was given 4 bars of chocolate and every boy was given 5 bars of chocolate. There were 5 times as many boys as girls at the party. Given that a total of 232 bars of chocolate were given out, how many boys were at the party?

Q2. Tin A contains some 20-cents coins and Tin B contains some 50-cents coins. There are 9 more coins in Tin A than Tin B. The amount of money in Tin A is $2.70 less than that in Tin B. How many 50-cents coins are there in Tin B?

As kids are not exposed to algebra at P4, I have solved the above problem sums using "Guess and Check" method. Does anyone have an alternative solution to share?

Thanks,

[atutor2001]

rocklee:

Q1. At a party, every girl was given 4 bars of chocolate and every boy was given 5 bars of chocolate. There were 5 times as many boys as girls at the party. Given that a total of 232 bars of chocolate were given out, how many boys were at the party?

Q2. Tin A contains some 20-cents coins and Tin B contains some 50-cents coins. There are 9 more coins in Tin A than Tin B. The amount of money in Tin A is $2.70 less than that in Tin B. How many 50-cents coins are there in Tin B?

Q1 Method - work in groups

Break the pupils into groups of 5 boys and 1 girl.
Each group would need = 5x5 (boys) + 1x4 (girls) = 29 bars

232 / 29 = 8 groups
8 x 5 = 40 boys

Q2 Method - make their numbers equal

Add 9 more 50c coins to B so that no. of coins is same as A
Additional money added to B = 9x 50 c = $4.50

With 9 more 50c coins in B, A will be less than B by = $2.70+$4.50 = $7.20

That is when both Tins have same number of coins, the Total difference = $7.20

Difference between 1 pair (i.e. one 50c and one 20c) = 50-20 = 30c

No. of pairs of coins = Total difference / Difference of 1 pair = 720/30 = 24 pairs

24-9=15 fifty cent coins (minus 9 to remove the 9 coins we have added in for easy calculation)

Both methods very clumsy - algebra gooood

[rocklee]

Hi atutor2001, thanks alot.

[christina soh]

tianzhu:

christina soh:

2. Ali has twice the amount of money than Bob. Bob has thrice the amount of money than Jim. If Ali has $40 more than Jim, how much money does Ali has ?

Hi

For your second question, due to time constraints, I’ll give some pointers for you to draw the MD.

Jim --- 1 unit
Bob ----- 3 units
Ali ----- 6 units

6 -1 ------- 5
5 units ------- 40
1 unit -------8

Ali ------- 6 units -------48

Best wishes

Thank you Tianzhu. Another question:-

There are 200 egss in Basket X and Basket Y. If you transfer 20 eggs in Basket X to Basket Y, there are still 14 more eggs in Basket X than Basket Y. How many eggs in Bakset X at first?

[tianzhu]

christina soh:

Thank you Tianzhu. Another question:-

There are 200 egss in Basket X and Basket Y. If you transfer 20 eggs in Basket X to Basket Y, there are still 14 more eggs in Basket X than Basket Y. How many eggs in Bakset X at first?

Hi

You're welcome.

Due to time constraints, I’ll give you some pointers without drawing the MD.

In the end, there are still 14 more eggs in Basket X than Basket Y.

Basket X ------- 107 eggs
Basket Y ------- 93

At first

Basket X ------107 + 20 --------127.

Best wishes

[Muffins]

christina soh:

Thank you Tianzhu. Another question:-


There are 200 egss in Basket X and Basket Y. If you transfer 20 eggs in Basket X to Basket Y, there are still 14 more eggs in Basket X than Basket Y. How many eggs in Bakset X at first?

If you transfer internally, the total will still remain as 200, so:

200 - 14 = 186

186 ÷ 2 = 93 → Y after the transfer

200 - 93 = 107

107 + 20 = 127

Hope this helped

[small]

MD..


http://farm6.static.flickr.com/5178/5455517613_b3034bd46a.jpg\">

[pertunia]

Hi, anyone can help to solve this question? This is from my son’s assignment. The question is:


Hassan has some pokemon cards to share among his friends. If he gives each friend 6 pokemon cards, he will have 5 cards left. If he gives each friend 8 pokemon cards, he will be short of 7 pokemon cards. How many pokemon cards does Hassan have?


My son is taught to use the guess and check method for questions similar to this. However, the space given for this question is too little. It is like the space for a short question. Can anyone solve this in a very easy manner without using algebra?


Thanks so much.

[small]

Hassan has some pokemon cards to share among his friends. If he gives each friend 6 pokemon cards, he will have 5 cards left. If he gives each friend 8 pokemon cards, he will be short of 7 pokemon cards. How many pokemon cards does Hassan have? \t\t\t\t\t


Gap : 5+7 = 12

Different = 8 - 6 = 2\t\t\t\t\t\t\t\t
12 / 2 = 6 friends\t\t\t\t\t
\t\t\t
From red font :
6 cards x 6 + 5 cards
= 41 cards\t\t\t\t\t\t

Hassan have 41 pokemon cards altogether.

[small]

pertunia:

Hi, anyone can help to solve this question? This is from my son's assignment. The question is:


Hassan has some pokemon cards to share among his friends. If he gives each friend 6 pokemon cards, he will have 5 cards left. If he gives each friend 8 pokemon cards, he will be short of 7 pokemon cards. How many pokemon cards does Hassan have?


My son is taught to use the guess and check method for questions similar to this. However, the space given for this question is too little. It is like the space for a short question. Can anyone solve this in a very easy manner without using algebra?


Thanks so much.

Hi pertunia,

HTH..

Multiple of 6 + 5 : 29, 35, 41, 47, 53
Multiple of 8 - 7 : 25, 33, 41, 49, 57\t

Hassan have 41 pokemon cards altogether.