Q&A - P4 Math

[KSP]

1. If I distribute 10 oranges to each of the children, I will be short of 30 oranges and if I distribute 8 oranges to each of them, I will be short of 6 oranges. How many oranges and children are there?


2. A had 6 times as much money as B at first. After both received $300 each, A has thrice as much money as B. How much did A and B have at first?

[tianzhu]

KSP:

1. If I distribute 10 oranges to each of the children, I will be short of 30 oranges and if I distribute 8 oranges to each of them, I will be short of 6 oranges. How many oranges and children are there?

Hi

First question touches on Gap and Difference.

Gap ----- 30 - 6 ------ 24
Difference ------ 10 - 8 ------- 2

Number of children ------- 24/2 ------ 12

Number of oranges -------- (12*10) - 30 ------ 90 or (12*8) - 6 ------90

You can see more examples of such questions in previous posts.

Best wishes

[tianzhu]

KSP:

2. A had 6 times as much money as B at first. After both received $300 each, A has thrice as much money as B. How much did A and B have at first?

Hi

Due to time constraints, I'll give some pointers to draw the MD.

Draw 6 boxes to show A’s money.
Draw 1 box to show B’s money.

A ------ (1unit)(1unit)(1unit)(1unit)(1unit)(1unit)
B ------ (1unit)

Add 300 to the first 6 boxes.
Add 300 to the 1 box (B)

Now,1 big box ------ 1 unit + 300

A ------ (1unit + 300)(1unit + 300)( (1unit + 300)
B ------ (1unit + 300)

Compare A’s money

3 units + 900 ------ 6 units +300
3 units ----- 600
1 unit ------ 200

A+B ------ 7 units ------- 7*200 ------1400

Best wishes

For P5/6 ----- In addition to MD, students may also use the Units Method.

[ttyh]

2 boys can sell as many durains as 3 girls. If 6 boys and 7 girls sold 192 durians altogether, how many durians did each boy sell?

[tianzhu]

ttyh:

2 boys can sell as many durains as 3 girls. If 6 boys and 7 girls sold 192 durians altogether, how many durians did each boy sell?

Hi

You may use “Number*Value”

Use a common multiple of 6 (2 and 3)

2 boys ----- 6 units
1 boy ------ 3 units

3 girls ------ 6 units
1 girl ------- 2 units

6 boys and 7 girls sold 192 durians altogether

(6*3) + (7*2) ------ 192
32 units ------ 192
1 unit ------ 6

1 boy ------ 3 units ------- 18

Best wishes

[cmm]

Sue has more than 50 hairpins.

If she puts them in packets of 7, she has 5 hairpins left.
If she puts them in packets of 9, she has 6 hairpins left.
How many hairpins does Sue have?

[alan000]

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cmm:

Sue has more than 50 hairpins.

If she puts them in packets of 7, she has 5 hairpins left.
If she puts them in packets of 9, she has 6 hairpins left.
How many hairpins does Sue have?

Dear cmm,

Hope this helps.

[cmm]

Many thanks, alan000!!!

[BigDevil]

tianzhu:

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Hi tianzhu,

Like CNS, I'm quite confused.

44 cars, 0 bicycle ----> 44 * 4 = 176 wheels
43 cars, 1 bicycle ----> 43 * 4 + 1 * 2 = 174 wheels

So why do you say that \"for every increase in 1 bicycle, the difference in the number of wheels drops by 6\"? Isn't it 176 - 174 = 2 wheels??

:? :?

[tianzhu]

BigDevil:

Like CNS, I'm quite confused.

44 cars, 0 bicycle ----> 44 * 4 = 176 wheels
43 cars, 1 bicycle ----> 43 * 4 + 1 * 2 = 174 wheels

So why do you say that \"for every increase in 1 bicycle, the difference in the number of wheels drops by 6\"? Isn't it 176 - 174 = 2 wheels??

Hi

There are 44 cars and bicycles. There are 128 more car wheels than bicycles. How many cars and bicycles are there?

43 cars ------ (43*4) ----- 172
1 bicycle ----- (1*2) ------ 2

Difference in number of wheels ------ (172-2) -------170

176 – 170 ------6

Please compare with this question.

There are 44 cars and bicycles. There are 128 wheels altogether. How many cars and bicycles are there?

In this case the difference is 2.

Best wishes