This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Friday, February 06, 2009

Tao Nan School P5 SA2 2007 Math Q48

There are some eggs in 3 baskets, A, B and C. 20% of the number of eggs in A is equal to 10% of the number eggs in B. The number of eggs in C is equal to 50% of the total number of eggs in A and B.

a) Express the number of eggs in C as a fraction of the number of eggs in B. (Leave your answer in its simplest form.)

b) If half of the eggs in B are taken out and placed into C, there will be 50 eggs in C. How many eggs are there in the 3 baskets?

Solution



a)
A + B ----- 15 units
C has 50% of 15 units ----- 15 units x 50/100 = 7.5 units

Fraction of number of eggs in C to B ----
7.5/10
= 75/100
= ¾ (Answer)

b)
If half of the eggs in B transferred to C -----
B ----- 10 units
Half of B ----- 5 units
C now will have, 7.5 units + 5 units ----- 12.5 units

12.5 units ----- 50 eggs
1 unit ----- 50 eggs divided by 12.5 = 4 eggs

Total number of eggs -----
A has 5 units
B has 10 units
C has 7.5 units
Total ----- 22.5 units

22.5 units ----- 22.5 x 4 = 90

Answer: There are 90 eggs in the 3 baskets.

20 comments:

Help needed said...

Can these problems be solved by Model Drawing ---

Q1) In Hall A, 30% of the 800 people were men. In Hall B 40% of the 400 people were women and children. After some of the people in both hall had switched hall, 25% of the people in Hall A and 75% of those in hall B were men. How many people were there in Hall B after the change?

Q2)During a warehouse book sale, Sally spent 62.5% of her money on 24 books and 18 pens. She also spent 25% of her remaining money on 18 files. Each pen costs 8/9 as much as the price of one book. The file costs $7.80 less than a book. Find the total cost of one book and one pen.

Anonymous said...

These problems can be easily solve using unit transfer method. I bought this book in this site:www.mathsheuristics.com

Anonymous said...

the first question can before and after concept: Totak unchanged

the second question use proportion concept by unit methd

xiaorou said...

Hi anonymous 0251/0253

Please show your full workings as it gives a chance for us to see your UTM method.

Must show some samples as promotion lah, just like selling kuehs kuehs during festive seasons

Anonymous said...

i am not selling the book, i am nie trainee, attend the seminar before. But i think you can ask him in his blog.

xiaorou said...

Can this problem be solved by Model Drawing?

Mr Lim spent $1496 on some comics and dictionaries altogether. The number of comics bought to the number of dictionaries bought was in the ratio of 3 : 2. A dictionary cost $4 more than a comic. The total cost of the comics was 20% more than the total cost of the dictionaries. Find the cost of a dictionary.

Anonymous said...

This can be solve by UTM under Proportion concept in less than 5 mins

Show me said...

Hi anon at 1033

Please show, don't tell.
Best Wishes

xiaorou said...

Hi anon @1033

Could you tell us more about UTM? Is it a new revolutionary method to solve PSLE Maths? Is it more effective than Model Drawing? Will it enable students to see Maths just like the pictorial representation in MD? Is it within MOE syllabus?

Could you show how UTM helps for the following questions?

1) Peter started his journey from Town A to Town B. If he travelled at a speed of 80 km/h, he will arrive at Town B 1/3 hours late. If he travelled at a speed of 60 km/h, he will arrive at Town B 3/4 hours late.
(a) Find the distance from Town A to Town B.
(b) How long will he take to cover the journey with a speed of 90 km/h?

2) A class of 40 pupils helped to carry bundles of old newspapers in an event organised to collect funds for the old folks. Each boy carried 3 stacks of newspapers and each girl carried 2 stacks. Altogether, the boys carried 30 more stacks than the girls. What is the ratio of the number of boys to number of girls in the class?

Anonymous said...

this was easy peasy!!!!

Anonymous said...

don't say like that

Anonymous said...

say,say,say yourself

Anonymous said...

how dare you say that to me???!!!

Anonymous said...

i do dare

Anonymous said...

well you don't know who i am???my name is anonmynus.

Anonymous said...

i know you,you are creacidi shen.

creacidi shen said...

how did you know??????!!!!!!!

Anonymous said...

it took me a minute to find that.i checked your idb blog of your account.to get there press start,click control panel.copy your subject and i'm done

creacidi shen said...

hey it's arijit. i know him.in my school he had the highest psle aggregate score of 281 three years ago.

Anonymous said...

what is these utm about?