Q&A - P5 Math

[hsm]

hi, can someone help on the below question:


At first, Ken had 1/5 as many marbles as Azrul. Then, Azrul gave 21- marbles to Ken. In the end, Ken had 2/3 as many marbles as Azrul.

a) What was the ratio of the marbles that Ken had at first to the no. of marbles Ken had in the end?

b) How many more marbles did Azrul have than Ken in the end?

The answer was provided but i still didnt get it.. :oops:
Can someone explain?


Answer: At first,
Ken => 1 unit => 5 parts (why they use the 5 multiplier?)
Azrul => 5 units => 25 parts

In the end,
Ken => 2 units => 12 parts ( why they use the 6 multiplier?)
Azrul => 3 units => 18 parts

Ratio = 5:12

Thanks

[tianzhu]

hsm:

hi, can someone help on the below question:


At first, Ken had 1/5 as many marbles as Azrul. Then, Azrul gave 21- marbles to Ken. In the end, Ken had 2/3 as many marbles as Azrul.

a) What was the ratio of the marbles that Ken had at first to the no. of marbles Ken had in the end?

b) How many more marbles did Azrul have than Ken in the end?

Hi

In this question, the total number of marbles remains the same before and after.Hence, the total number of units showing the number of marbles must be the same.

A common multiple of 5 and 6 is 30.

In the beginning
Ken ----- 1 unit ------------- 5 units
Azrul ----- 5 units ---------- 25 units
Total ----- 6 units ---------- 30 units

In the End
Ken ----- 2 unit ------------- 12 units
Azrul ----- 3 units ----------- 18 units
Total ----- 5 units ------------ 30 units

a)The ratio of the marbles that Ken had at first to the no. of marbles Ken had in the end ------ 5:12

b) 12 – 5 ----- 7

7 units ----- 21
1 unit ----- 3

6 units ----- 18

Best wishes

[hsm]

Many thanks Tianzhu you are my saviour

[Chan09]

Need some help as used UTM method but couldn’t get answer:

The no. Of pupils in the hall is twice the no. In the canteen. 3/4 of the pupils in the hall were boys and 3/5,of the pupils in the canteen were girls. If there are 6 more girls in the canteen than the hall, find no. Of pupils in the hall?
Ans: 120

[lizawa]

Chan09:

Need some help as used UTM method but couldn't get answer:

The no. Of pupils in the hall is twice the no. In the canteen. 3/4 of the pupils in the hall were boys and 3/5,of the pupils in the canteen were girls. If there are 6 more girls in the canteen than the hall, find no. Of pupils in the hall?
Ans: 120

Just use ratio to solve this.

Hall : canteen
= 2 : 1
= 20 : 10
Hall boys : girls
= 15 : 5

Canteen boys : girls
= 4: 6

1u = 6
20u = 120

[Chan09]

Need some guidance as whether this can be solved used UTM:

J and P had a sum of money. J gave P 0.4 of her money. P then gave J 1/2 of her money. In the end, J had three times the amt of money that P had. If J gave P $125 more than what P gave J , how much money did J have at first?
ans: $1250

[MathIzzzFun]

Chan09:

Need some guidance as whether this can be solved used UTM:

J and P had a sum of money. J gave P 0.4 of her money. P then gave J 1/2 of her money. In the end, J had three times the amt of money that P had. If J gave P $125 more than what P gave J , how much money did J have at first?
ans: $1250

Hi

Use \"work backwards\" heuristics... any method can then be used.

There are two transfers in the question - so, work each one in turn. Start with the last one which gives us the final situation ie
J = 3 blocks
P = 1 block

Look at the transfer before this... ie P gave 1/2 of her money to J --> this means P is left with 1/2 her money = 1 block, so before P gave her money to J, P had 2 blocks. So we have, before P gave her money to J:
J = 2 blocks
P = 2 blocks
which is after J gave 0.4 (2/5) of her money to P ie J is left with 3/5 ... now divide each block into 3 --> 1 block = 3 units :
J = 6 units
P = 6 units
so, 3/5 of J money = 6 units,
J's money = 10 units
2/5 of J money = 4 units


P gave 1 block = 3 units.

So, 4 units - 3 units = 1 unit = 125, 10 units = $ 1250

J had $ 1250 at first.

cheers.

[Chan09]

I have got 2 more that I need help:

1) mr tan monthly salary is twice mr lee. His monthly savings is 6 times mr lee. Given both of them spend $1000 monthly, how much money does mr tan earn?
Ans 2500

2) out of the 40000 people, 30% were women, 10% children and rest men. Some women left the show with half the no. Of children before it ended. As a result the % of men increased to 75% of the people at the show at the end. How many women were at the show at the end?
Ans 6000

Thank you

[tianzhu]

Chan09:

1) mr tan monthly salary is twice mr lee. His monthly savings is 6 times mr lee. Given both of them spend $1000 monthly, how much money does mr tan earn?
Ans 2500

Hi

You may use MD or Units Method.

Salary
Mr Tan ----- 2 --------- 10
Mr Lee ----- 1---------- 5
Difference -----1------ 5

Monthly savings
Mr Tan ----- 6
Mr Lee ----- 1
Difference ----- 5 ------ 5

Since they spent the same amount of $1000 monthly, the difference in the amount of money stays the same (Constant Difference)

Make the difference in number of units the same.

10 - 6 ----- 4
(5 - 1 ----- 4)

4 units ----- 1000

1 unit ----- 250

10 units ------ 2500 (Mr Tan’s salary)

Best wishes

[tianzhu]

Chan09:

2) out of the 40000 people, 30% were women, 10% children and rest men. Some women left the show with half the no. Of children before it ended. As a result the % of men increased to 75% of the people at the show at the end. How many women were at the show at the end?
Ans 6000

At first
Women ----- 30% ------ 12000
Children ----- 10% ------ 4000
Men ------ 60% ------- 24000

In the end
Children ------ 2000
Men ------ 24000 (75%)

75% ------ 24000
1% ------ 320

Women ------ 25% ------- 8000

Number of women at the end of the show ------ 8000 – 2000 ------ 6000

Best wishes