Tutor MathsGuru: Ask me for your burning Maths questions!

[freakmum]

Mathsguru, how to solve this question?

If alan gives ben 6 sweets, the ratio of the number of sweets Alan will have to the number of sweets Ben will have is 2:5.
If Ben gives alan 8 sweets, the ratio of the number of sweets alan will have to the number of sweets ben will have is 1:2.
How many sweets did alan have at first?

[KSP]

Hi mathsguru, I have the working for these 2 questions from Dharma but can you show me the model method to solve them? Thanks.


1. Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles. How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red? Ans: 350


2. In a math competition, participants can obtain 4 possible award: Gold, Silver, Bronze and Participation. 3/7 of the participants obtained Gold awards, 1/4 of the them obtained Silver awards, and 1/6 of them obtained Bronze awards. Given that there were less than 100 participants taking the competition,
a) How many participants obtained the awards for Participation? Ans: 13
b) How many more participants obtained Gold awards then Bronze awards? Ans: 22

[starlight1968sg]

Hi folks,

I need some help on p5 questions:

1) A greengrocer had 75 more apples than oranges at first. After selling 4/5 of the apples and 3/4 of the oranges, he had 285 fruits left.
(a) How many apples did he sell?
(b) What fraction of the fruits sold were oranges?
(ans: 540;5/11)

2) Ben and Caleb read a total of 60 books in November. In December, Ben read 15 fewer books than Caleb who read thrice as many books as he did in November. If both of them read a total of 90 books in December, how many books did Ben read in Nov and Dec?
(ans: 78 books)

MTIA.

[mathsguru]

firebird:

3) A marathon runner has some water in his water bottle. Every time he comes to a refill station, he doubles the amount of water in his bottle.

Every time he comes to a rest stop, he drinks 500ml of his water.
During one race, the marathon runner passes a refill station and a rest stop three times. After the third rest stop, he finds his water bottle empty.

How much water did he have in the bottle at the begining of the race?

Hi Firebird,

Here's my solution for Question 3.

Regards,
MathsGuru

http://www.postimage.org/image.php?v=aVkUNjA

[mathsguru]

help:

Please help to solve the problem using model


In a bag, there are red, yellow and blue marbles. There were twice as many red marbles as yellow marbles and twice as many yellow marbles as blue marbles at first. After removing 15 blue marbles and some yellow marbles from the bag, the number of red marbles became thrice that of the yellow marbles but the number of yellow marbles was still twice that of the blue marbles. What was the total number of marbles in the bag at first?[/size]

Hi Help,

Here's my solution. Hope it helps!


MathsGuru

http://www.postimage.org/image.php?v=aVkZP5J

[mathsguru]

KSP:

Hi Mathsguru and everyone,


I came across this maths book Unit Transfer Method - Mastering Heuristic Series by Sunny Tan, Price S$37.50 which I find it very helpfut and easy to understand. Have you seen this book before and what is your comment? Thanks.

Hi KSP,

I think I've seen this book before. To be honest, I think it can be rather informative to parents who wants to know more about using diagrams, etc to solve problems and to teach their children. However, as it is presented in a rather structured & textbook style, it may look intimidating for primary school students to do self-learning. Hence, I would think it's more suitable for parents rather than students. And frankly speaking, I think it's over-priced. Some assessment books also feature heuristics methods and examples and they only cost ard $10.

But of course, if it helps to enlighten one in some ways or other, I guess it's money well-spent.

My 2 cents' worth,
MathsGuru

[mathsguru]

ttyh:

I'm sorry, I didn't meant to be funny. But my 8yrs old ds answered (1) but got it wrong...

Pls....teach me!!

The difference between 516 and ? is 381.
What is the missing number in the box above?
(1) 135
(2) 137
(3) 877
(4) 897

Hi TTYH,

Answers can be both 516 - 381 = 135 (1) and 516 + 381 = 897 (4). You should clarify with your child's teacher.

Regards,
MathsGuru

[mathsguru]

firebird:

Dear mathsguru


Good morning.

Please help me on the following question:

1) There were 850 marbles in box A and 70 marbles in Box B. When an equal number of marbles were added into each box, the ratio of the number of marbles in A to that in B is 5:1.
How many marbles were added into both boxes?

I tried this quesion for an hour or so, I give up.

Many thanks
firebird

Hi Firebird,

Here's my solution.


MathsGuru

http://www.postimage.org/image.php?v=PqzE1Ii

[mathsguru]

KSP:

Hi mathsguru, I have the working for these 2 questions from Dharma but can you show me the model method to solve them? Thanks.


1. Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles. How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red? Ans: 350


2. In a math competition, participants can obtain 4 possible award: Gold, Silver, Bronze and Participation. 3/7 of the participants obtained Gold awards, 1/4 of the them obtained Silver awards, and 1/6 of them obtained Bronze awards. Given that there were less than 100 participants taking the competition,
a) How many participants obtained the awards for Participation? Ans: 13
b) How many more participants obtained Gold awards then Bronze awards? Ans: 22

Hi KSP,

Actually I've solved Question 1 before, but I guess you must have missed it. Here's the solution:

http://www.postimage.org/image.php?v=aVl7LP0

As for question 2, I'm afraid my recommended solution is not to draw models but rather, use fractions to solve. This is a good example of a question that will take a long time to draw the model since the common denominator is very big. Nevertheless, if you wanna see a simple visual representation, I've it here:

http://www.postimage.org/image.php?v=aVlcQ5i

Cheers,
MathsGuru

[CoffeeCat]

freakmum:

Mathsguru, how to solve this question?

If alan gives ben 6 sweets, the ratio of the number of sweets Alan will have to the number of sweets Ben will have is 2:5.
If Ben gives alan 8 sweets, the ratio of the number of sweets alan will have to the number of sweets ben will have is 1:2.
How many sweets did alan have at first?

There are many ways to solve such a question, notably using models or algebra. However I will use the ratio method.

In ratio questions, its best to find a \"common denominator\" or sth that stays constant in both ratios. In other questions its the difference, in this its the total number of sweets.

Ratio of the no. of sweets
after the first transfer Alan : Ben : Total
2 : 5 : 7
= 6 : 15 : 21

after the second transfer 1 : 2 : 3
= 7 : 14 : 21

Notice that the no. of sweet Alan had in reality is somewhere between the 6 units worth and 7 units worth. When he gave away 6 he will have 6 units worth and when he received 8 he will have 7 units worth. Therefore 1 unit worth of sweets = 6+ 8 = 14.
no. of sweets alan had at first = (6*14) + 6 = 90