Q&A - P5 Math

[Jamesbond]

A group of 24 children sold some tickets for a charity show. Each ticket was sold at $5. Each boy sold 5 tickets and each girl sold 3 tickets. The boys collected $40 more than the girls.

a) How many girls were there in the group?
b) How many tickets were sold altogether?

TIA

[PapayaDad]

Assume 12B and 12G

So Boys sold 60 tickets ; girls sold 36 tickets
So boys get $300 ; girls get $180
Boys get 120 more ; we need to reduce this to 40 only ie need to reduce 80

If we reduce 1 boy ; we reduce five tickets ; which is reduce $25
But there will be one more girl ; ie 3 more tickets ; which is $15 more.
So the difference is reduce by $40

So we need to reduce 2 boys from our initial assumption.


Answer 10 boy 14 girls

Check
10B = 50 tickets = $250
14G = 42 tickets = $210
Correct, boys collected $40 more.
There are 14 girls.
Total tickets sold is 92

[ChewingPencilLine]

tianzhu:

veraclari:

HI SORRY shd be Jane's spending. . Fjanks for helping in e questions. . But girl asking me how to draw model too... really got me siah.. model me cannot. .. ha ha h

Hi

Good Morning.

There are alternative ways to present the MD.I've shown two options.

Hope your girl will find it useful.

Best wishes

http://farm9.staticflickr.com/8115/8607173179_2eb41f9ca3_z.jpg\">

Just going to point out that you are assuming that they spent everything they brought. You might think this a moot point but I was confounded when I first read this question, ._.

Cheers.

[veraclari]

Wow Thanks All for ur help! The model part is really killing me.. really appreciate the MD here which makes everything so clear.. now shd ask my girl to attempt e other MD for e first qn on pears and plums again as we re both clueless nd couldn't draw one that incorporated everything. .

[Jamesbond]

PapayaDad:

Assume 12B and 12G

So Boys sold 60 tickets ; girls sold 36 tickets
So boys get $300 ; girls get $180
Boys get 120 more ; we need to reduce this to 40 only ie need to reduce 80

If we reduce 1 boy ; we reduce five tickets ; which is reduce $25
But there will be one more girl ; ie 3 more tickets ; which is $15 more.
So the difference is reduce by $40

So we need to reduce 2 boys from our initial assumption.


Answer 10 boy 14 girls

Check
10B = 50 tickets = $250
14G = 42 tickets = $210
Correct, boys collected $40 more.
There are 14 girls.
Total tickets sold is 92

:thankyou: PapayaDad.

[Jamesbond]

A box contained a number of 20 cent and 50 cent coins in the ratio 3:4. When ten 50 cent coins were taken out and replaced by 20 cent coins, the ratio became 7:5. Find the sum of money in the box at first?

Pl help.

[MathIzzzFun]

Jamesbond:

A box contained a number of 20 cent and 50 cent coins in the ratio 3:4. When ten 50 cent coins were taken out and replaced by 20 cent coins, the ratio became 7:5. Find the sum of money in the box at first?

Pl help.

possible approaches - cross-multiply/UP, units, MD.

Using units:

10 x $0.50 = 25 x $0.20
--> 10 fifty-cent coins were replaced by 25 twenty-cent coins

At first
number of 50c --> 20 units + 10
number of 20c (= 3/4 number of 50c) --> 15 units + 7.5

In the end,
number of 50c --> 20 units
number of 20c (=7/5 number of 50c) --> 28 units

since 25 twenty-cent coins were added, we have:

15 units + 7.5 + 25 = 28 units
1 unit --> 2.5

Sum of money in the box at first
= sum of money in the box in the end
= 20 x 2.5 x $0.50 + 28 x 2.5 x $0.20
= $39

cheers.

[snowball]

4/7 of Ming’s mass is equal to 2/5 of Rob’s mass.

If Ming puts on 6 kg and Rob loses 12kg, the two men will have the same mass.
a) Draw a clearly labelled model to solve the problem.
b) What is Rob’s mass?

[snowball]

In January, Mrs Wong spent 2/5 of her salary on rent and $120 on parking fees.

She spent 1/4 of her remaining salary on food and $480 on shopping.
She saved the remaining $1896.
How much was Mrs Wong’s salary for January ?

[MathsOlympiadtrainer]

snowball:

In January, Mrs Wong spent 2/5 of her salary on rent and $120 on parking fees.

She spent 1/4 of her remaining salary on food and $480 on shopping.
She saved the remaining $1896.
How much was Mrs Wong's salary for January ?

This is a working backwards qn.
3/4 of her remaining salary-> 480+1896= 2376
4/4 of her remaining salary-> 2376/3 * 4= 3168

3/5 of her salary-> 3168+120 = 3288
5/5 of her salary-> 3288/3 * 5 = 5480

Hope that helps.