Q&A - P5 Math

[MathIzzzFun]

Another question:

Mufaddal wants to make a square by piecing rectangular cards together, each measuring 7 cm by 5 cm. What is the least number of cards he needs to make a square?

Hi tracywham,

The smallest square should be a 35 cm by 35 cm square.

(Lay out the cards in 5 columns and 7 rows)

So he needs 5 x 7 = 35 cards.


Hope this helps.

Cheers



speedmaths
.

Hi. I got the same answer. But the teacher gave the answer as 6 cards.

since the question did not state that the cards are to be arranged without overlapping and with no gap, then min number is 4 cards as follows:



cheers.

[belnanna]

Totally got me.. Please help..Thanks


In a school science fair, there were exhibits from class A , class B and class C. Altogether, 25 exhibits came from class B and class C. In a total of 16 exhibits were not from class C and a total of 15 exhibits were not from class B.
How many exhibits were there altogether?

[jo-jed]

MathIzzzFun can help?


Mr Lee had a sum of money.On Monday,he spent 1/5 of his money and then lost a $2 note.On Tuesday,he spent 1/3 of his remaining money on 3 identical bags of rice.On wednesday,he bought another 4 such bags of rice.He had $21.60 left in the end.Find the sum of money he had at first.

Thanks

[belnanna]

Can the genius help me please..

The length of a rectangular pond is 14 m and its breadth is 7 m. Fatimah wants to build a running path around the pond. The width of the path is 1/2 m. what is the area of the running path?

[MathIzzzFun]

Need help with one more question :

source of question ?

more than 1 possible solution...here are 3 of them:
1) girls : boys = 2:3
4 girls @18 clips/girl --> total clips for girls = 72
6 boys @6 clips/boy --> total clips for boys = 36
total number of clips =108
ratio of clips for each girl:each boy = 18:6 = 3:1

2) girls : boys = 4:15
4 girls @12 clips/girl --> total clips for girls = 48
15 boys @4 clips/boy --> total clips for boys = 60
total number of clips =108
ratio of clips for each girl:each boy = 12:2 = 3:1

2) girls : boys = 1:6
4 girls @9 clips/girl --> total clips for girls = 36
24 boys @3 clips/boy --> total clips for boys = 72
total number of clips =108
ratio of clips for each girl:each boy = 9:3 = 3:1


cheers.

[MathIzzzFun]

Please help

Mr Lee had a sum of money.On Monday,he spent 1/5 of his money and then lost a $2 note.On Tuesday,he spent 1/3 of his remaining money on 3 identical bags of rice.On wednesday,he bought another 4 such bags of rice.He had $21.60 left in the end.Find the sum of money he had at first.

work backwards...

1/3 of remaining money buys 3 identical bags of rice.
so, all of remaining money can buy 9 identical bags of rice.
total number of bags of rice bought with remaining money = 7, with $21.60 left --> which can buy another 2 bags of rice,

2 bags of rice --> $21.60
1 bag of rice --> $10.80
remaining money --> 9 x $10.80 = $97.20 --> this is the amount of money left after spending 1/5 of money and losing $2.

so, 4/5 money = $2 + $97.20 = $99.20
total amount of money at first = $99.20/4 x 5 = $124

cheers.

[MathIzzzFun]

Totally got me.. Please help..Thanks


In a school science fair, there were exhibits from class A , class B and class C. Altogether, 25 exhibits came from class B and class C. In a total of 16 exhibits were not from class C and a total of 15 exhibits were not from class B.

How many exhibits were there altogether?

16 exhibits not from C --> 16 exhibits from A and B
15 exhibits not from B --> 15 exhibits from A and C
So, B has 1 more exhibit than C

25 exhibits from B and C
So, C --> (25-1)/2 = 12
Total A+B +C = 16+12 = 28

Alternatively,
A+B =16
A+C= 15
B+C =25

Adding all three will give two sets of (A+B+C)
A+B+C =(15+16+25)/2 = 28

cheers.

[belnanna]

Totally got me.. Please help..Thanks


In a school science fair, there were exhibits from class A , class B and class C. Altogether, 25 exhibits came from class B and class C. In a total of 16 exhibits were not from class C and a total of 15 exhibits were not from class B.

How many exhibits were there altogether?

16 exhibits not from C --> 16 exhibits from A and B
15 exhibits not from B --> 15 exhibits from A and C
So, B has 1 more exhibit than C

25 exhibits from B and C
So, C --> (25-1)/2 = 12
Total A+B +C = 16+12 = 28

Alternatively,
A+B =16
A+C= 15
B+C =25

Adding all three will give two sets of (A+B+C)
A+B+C =(15+16+25)/2 = 28

cheers.

awesome explaination.. Thanks a zillion!

[speedmaths.com]

Another question:

Mufaddal wants to make a square by piecing rectangular cards together, each measuring 7 cm by 5 cm. What is the least number of cards he needs to make a square?

Hi tracywham,

The smallest square should be a 35 cm by 35 cm square.

(Lay out the cards in 5 columns and 7 rows)

So he needs 5 x 7 = 35 cards.


Hope this helps.

Cheers



speedmaths
.

Hi. I got the same answer. But the teacher gave the answer as 6 cards.

Hi,

Maybe you can show us the teacher's solution, and we can all learn from it.

The area of 1 card is 35 cm sq.

The area of 6 cards will be 6 x 35 = 210 cm sq.

210 is not a square number.


If overlapping is allowed, then you just need 2 cards to get a 7 cm by 7 cm square.

If you can fold or cut, then you just need 1 card to get a 5 cm by 5 cm square.


Anyway, we shall wait for the teacher's solution.

Cheers


speedmaths
.

[tracywham]

Hi,

Maybe you can show us the teacher's solution, and we can all learn from it.

The area of 1 card is 35 cm sq.

The area of 6 cards will be 6 x 35 = 210 cm sq.

210 is not a square number.


If overlapping is allowed, then you just need 2 cards to get a 7 cm by 7 cm square.

If you can fold or cut, then you just need 1 card to get a 5 cm by 5 cm square.


Anyway, we shall wait for the teacher's solution.

Cheers


speedmaths
.[/quote]

Suspect my gal had copied or heard the answer wrongly. Had asked her to check with friends or teacher today.