Tutor MathsGuru: Ask me for your burning Maths questions!

[jieheng]

Jcong:

A container of red dye weighs 2.27 kg when it is 1/3 full. Another identical container of red dye weighs 4.8 kg when it is 6/7 full. What is the weight of the empty container?

1/3 -----> 7/21

6/7 -----> 18/21

the capacity of the container is 21u

weight of empty container + 7u -----> 2.27 [when the contaner is 7/21 (1/3) full]


weight of empty container + 18u -----> 4.8 [when the contaner is 18/21 (6/7) full]

weight of empty container + 7u + 11u -----> 4.8

2.27 + 11u -----> 4.8

11u -----> (4.8 - 2.27) = 2.53

1u -----> 2.53 / 11 = 0.23

weight of empty container + 7u -----> 2.27

weight of empty container + 7*0.23 -----> 2.27

weight of empty container -----> (2.27 - 1.61) = 0.66 kg (Ans)

[MathIzzzFun]

YumYum:

HappyFaye:

Ok, let me try again.


In this case, 'Broken' Model is used as we do not know how many units/boxes to draw.

First construct a 'broken' model of a multiple of 10 with 15 left

When each children were given 12 marbles, it is the same as each child is getting another 2 more marbles. We can then construct another 'broken' model of a multiple of 4 + multiple of 2 with 1 left.

So 15 - 1 = 14 marbles.

Since 14 marbles were given to the number of children of 2 more marbles each,
14 marbles / 2 --> 7

So 7 children have 2 more marbles each.

So there are 7 children.

If each child has 10 marbles, total marbles --> (10 x 7) + 15 = 85
The answer is the same if each child has 12 marbles.

Hope this is not too confusing, without the broken models drawn here.

Thank you for the detailed explanation. Sorry, what is \"broken model\"? I just got hold of the book \"Challenging Maths Made Easy\" to educate myself on the various Maths techniques, still gropping in the dark...

Can I check on why we need to divide 14/2, a bit lost here... thks

Hi YumYum,


The key here is to work on the additional marbles that each child gets and the number of marbles left over.

\"If each child were given 10 marbles, there would be 15 marbles left over.\" >> Every child gets 10 marbles, 15 left over.

\"If each child were given 12 marbles, there would be 1 marble left over. \" >> Every child gets 2 more marbles, 1 left over.

So, the question can be rephrased as :\"I have 15 marbles. If I were to give each child 2 marbles, I will have one marble left. How many children are there ?\"

>> number of marbles given = 15 -1 =14. Each child gets 2 marbles more, number of children = 14 /2 = 7

cheers.

[CJM]

Mrs ho used a total of 5/6 kg of sugar in march and April. She used 7/12kg more sugar in march than in April. How much sugar did she use in April?

[CJM]

Mr Goh is 3 times as old as his daughter who is 12 years old. What will be their total age in 13 year’s time?

[Daddy]

Hi,


Need help on the question.

Jason, Kelvin and Lily had a total of 161 stamps at first. Jason gave away 1/5 of his stamp. Kelvin received 34 more stamps. Lily bought some more stamps and hence tripled her original number of stamps. Then, the ratio of the number of stamps Jason, Kelvin and Lily had was 2:3:6. How many stamps did Kelvin have at first.


Thanks.
Daddy

[jieheng]

CJM:

Mrs ho used a total of 5/6 kg of sugar in march and April. She used 7/12kg more sugar in march than in April. How much sugar did she use in April?

March + April = 5/6

March + March + 7/12 = 10/12

March = (3/12) / 2 = 3/24

April = March + 7/12 = 3/24 + 7/12 = 3/24 + 14/24 = 17/24 kg (Ans)

[jieheng]

CJM:

Mr Goh is 3 times as old as his daughter who is 12 years old. What will be their total age in 13 year's time?

Daughter = 12 yrs old

Father = 3 * 12 = 36 yrs old

Their total age in 13 year's time = 12 + 36 + 13*2 = 74 (Ans)

[jieheng]

Daddy:

Hi,


Need help on the question.

Jason, Kelvin and Lily had a total of 161 stamps at first. Jason gave away 1/5 of his stamp. Kelvin received 34 more stamps. Lily bought some more stamps and hence tripled her original number of stamps. Then, the ratio of the number of stamps Jason, Kelvin and Lily had was 2:3:6. How many stamps did Kelvin have at first.


Thanks.
Daddy

J 2u
K 3u
L 6u

J 4u (4/5 after gave away 1/5)
K 6u
L 12u

At First
J 5u (4u+1u)
K 6u-34
L 4u (12u/3)

total= 5u + (6u-34) + 4u -----> 161

15u -34 -----> 161

15u -----> 195

1u -----> 13

Number of stamps that Kelvin had at first = 6u - 34 = 6*13 - 34 = 78 - 34 = 44 (Ans)

[YumYum]

hi,


Can anyone pls assist with the foll Qns:

1. I have 190 Singapore and Malaysia stamps altogether, of which 147 are floral stamps. 3/4 of my Singapore stamps are floral while 5/6 of my Malaysia stamps are floral. How many Singapore stamps do I have?

2. The total number of pupils in the two classes 6A and 6B is 84. 5/8 of 6A pupils and 3/4 of 6B pupils add up to 58. Fing the number of pupils in 6B.

3. Allan had 60 more stamps than Becky. They each gave some of their stamps to their friends. The number of stamps Becky gave away was 2/5 of the number of stamps Allan had at first; the number of stamps Allan gave away was 2/3 of the number of stamps Becky had at first; Both had an equal number of stamps left. How many stamps did Allan have at first?

many thanks. :lol:

[Daddy]

Hi jieheng,


How did you get
[quote]Jason, Kelvin and Lily had a total of 161 stamps at first. Jason gave away 1/5 of his stamp. Kelvin received 34 more stamps. Lily bought some more stamps and hence tripled her original number of stamps. Then, the ratio of the number of stamps Jason, Kelvin and Lily had was 2:3:6. How many stamps did Kelvin have at first. [/quote][quote]J 2u
K 3u
L 6u

J 4u (4/5 after gave away 1/5)
K 6u
L 12u

At First
J 5u (4u+1u)
K 6u-34
L 4u (12u/3)

total= 5u + (6u-34) + 4u -----> 161
15u -34 -----> 161
15u -----> 195
1u -----> 13
Number of stamps that Kelvin had at first = 6u - 34 = 6*13 - 34 = 78 - 34 = 44 (Ans)[/quote]How did you get Kelvin 6u & Lily 4u? Sorry, I did not understand?