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[MathIzzzFun]

Essential:

Math Guru, pls help me with this question

Renjie has three ropes with length of 144,168 cm and 252cm. He wants to cut the three ropes into shorter pieces of equal length with no remainders a) what is the greatest possible length of each of the shorter pieces? b) how many of the shorter pieces of equal length can he get?

Hi

not math guru..mathizzzfun here..

this question is about HCF = highest common factor.

The standard way is the list out the factors for each number and then pick up all the common factors.

However, for these 3 numbers, we could tak a little short cut..
first, we see that all the 3 numbers are divisible by 3 (test divisibility by 3 --> sum of digits divisible by 3) and all numbers are also divisible by 4 (test divisibility by 4 --> last 2 digits divisible by 4)

So, 4x3 =12 is a factor for all the numbers...
144 = 12 x 12 = 12 x 2 x 2 x 3
168 = 12 x 14 = 12 x 2 x 7
252 = 12 x 21 = 12 x 3 x 7
There are no more common factor, so 12 is the HCF --> Longest length for each piece = 12 cm
Number of 12cm pieces = 12 + 14 + 21 = 47

cheers.

[Essential]

Thank u Marhizzzfun

[MathIzzzFun]

Essential:

Thank u Marhizzzfun

u r welcome

cheers.

[kwcllf]

Hi please help with the following question.


Roy, Sam and Ted had a sum of money. Roy had 4/5 of Sam’s money. Sam had 60% of Ted’s. After Roy gave $12 to Sam, he had 5/7 of what Sam had. How much more money did Ted have than Sam in the end?

Thanks:-)

[Essential]

Hi, Need help on this question.

1) A rectangular cardboard measures 33 cm by 24 cm. What is the maximum number of rectangular pieces that can be cut from the cardboard if each piece of rectangle measures t6 cm by 4cm? Please help me confirm the answer is 28 , 32 , 30 or 34
Thanks.

[kwcllf]

Please help with the following question:


Jerry bought four times as many pencils as notebooks and spent a total of $21.60. He spent $2.40 more on notebooks than the pencils. Given that a notebook cost $3.20 more than a pencil, find the cost of a pencil. Thanks!

[MathIzzzFun]

kwcllf:

Please help with the following question:


Jerry bought four times as many pencils as notebooks and spent a total of $21.60. He spent $2.40 more on notebooks than the pencils. Given that a notebook cost $3.20 more than a pencil, find the cost of a pencil. Thanks!

Hi

Just came back from a trip..

First, find how much is spent on Pencils and Notebooks.
Amount spent on Pencils = [C]
Amount spent on Notebooks = [C][$2.40]

So, 2[C] + $2.40 = $21.60, [C]= $9.60
Amount spent on Pencil= $9.60
Amount spent on Notebooks = $9.60+ $2.40= $12.00

Number of pencils bought is 4 times as many as notebook--> ie we have 4 packs of pencils and 1 pack of notebooks and each pack contains same number of pencils/notebooks.

Each pack of pencils cost $9.60 / 4 = $ 2.40
Each pack of notebooks cost $12.00 --> $12.00 - $2.40= $9.60 than each pack of pencils.

Since each notebook cost $3.20 more than a pencil, so number of notebooks/pencils in each pack = $9.60/$3.20 =3

So, cost of each pencil = ocst of each pack of pencils / number of pencils in each pack = $2.40/3 = $0.80

cheers.

[MathIzzzFun]

Essential:

Hi, Need help on this question.

1) A rectangular cardboard measures 33 cm by 24 cm. What is the maximum number of rectangular pieces that can be cut from the cardboard if each piece of rectangle measures t6 cm by 4cm? Please help me confirm the answer is 28 , 32 , 30 or 34
Thanks.

Hi

34 is out because 33 x 24 / (6x4) = 33

The max number possible is 32- first cut out 24cm by 24cm --> 24/6 x 24/4 = 24 pieces

The remaining piece is of dimension 9 cm x 24 cm --> cut out 8 cm x 24cm --> 8/4 x 24/6 = 8 pieces

Total 32 pieces, leaving a strip of 1cm x 24cm

cheers.

[MathIzzzFun]

kwcllf:

Hi please help with the following question.


Roy, Sam and Ted had a sum of money. Roy had 4/5 of Sam's money. Sam had 60% of Ted's. After Roy gave $12 to Sam, he had 5/7 of what Sam had. How much more money did Ted have than Sam in the end?

Thanks:-)

Hi

initially
roy : sam = 4 : 5

in the end,
roy: sam = 5 : 7

total amount that roy and sam had remained the same so make the total the same
initially, roy : sam = 4:5 = 16u : 20u
in the end, roy: sam = 5:7 = 15u: 21u
so, 1u = $12
Sam, at first = 20u = $ 240, Ted = 5/3 x $240 = $400
Sam, in the end = 21u = $252
... I think you can complete the rest..

cheers.

[kwcllf]

Hi MathIzzzFun,


Thanks again. Missed your expertise. Hope you had a great trip!