Q&A - PSLE Math

[anneshirleygilbert]

Hello tianzhu,


Patrick, Devi and Jiamin each have the same number of beads. How many beads must Devi give to Patrick and Jiamin so that Patrick has 20 beads more than Devi and Jiamin has 4 fewer beads than Patrick?

Can you please show how you arrived at the answer 12? Did Devi give a total of 12 marbles to Patrick and Jiamin?

TIA.
Anne

[2632parent]

Need help on this simple question, I just cannot get the answer.


1) A piece of raffia measuring 7 m long was cut into smaller pieces. Each piece was 5/8 m long. What is the length of the remaining raffia?

Thank you.

[tianzhu]

2632parent:

Need help on this simple question, I just cannot get the answer.


1) A piece of raffia measuring 7 m long was cut into smaller pieces. Each piece was 5/8 m long. What is the length of the remaining raffia?

Thank you.

Hi

Look at it this way.

Divide 7m into 7 equal sections of 1m each.

Now consider one 1m section and divide into 8 parts.

Each piece was 5/8 m long, so we need to cut 5 parts to make one piece.

7m ------- 7 number of 1m section -------- 56 parts

We can cut 55 parts with a remainder of 1 part.

Hence, the remaining length is 1/8

Best wishes

[tianzhu]

anneshirleygilbert:

Can you please show how you arrived at the answer 12? Did Devi give a total of 12 marbles to Patrick and Jiamin?

TIA.
Anne

Hi

8 to Patrick and 4 to Jiamin,giving a total of 12 beads.

I'll try to prepare some sketch and PM to you at a later time.

Best wishes

[Michaelia0816]

Pls help with this question,

1) A number has 3 digits. When it is divided by 6 or 7, it leaves a remainder of 1. When it is divided by 8 or 11, it leaves a remainder of 7. What is the largest such number?

2) A rectangle of length 24 cm is given as shown below. Twelve identical isoceles triangles are cut from it. The perimeter of the remaining figure is 120 cm more than that of the rectangle. Find the perimeter of an isoceles triangle?

Picture of the figure for Q2:
http://t.co/lUBjqv11

[Michaelia0816]

2632parent:

Need help on this simple question, I just cannot get the answer.


1) A piece of raffia measuring 7 m long was cut into smaller pieces. Each piece was 5/8 m long. What is the length of the remaining raffia?

Thank you.

Hi, this is the simple question,

Solution:
7m=700cm
5/8m= 62.5 cm
700cm/62.5cm=11 Remainder 12.5 cm

Answer: 12.5 cm

[tianzhu]

Michaelia0816:

Pls help with this question,

1) A number has 3 digits. When it is divided by 6 or 7, it leaves a remainder of 1. When it is divided by 8 or 11, it leaves a remainder of 7. What is the largest such number?

Hi

You may use “SL” to do this question.

Find multiples of 42 + 1

Similarly find multiples of 88 + 7

Do a listing, the answer is 799.

I believe you can use your calculator for this question, so with a bit of planning, it’s not too tedious.

Another way, with some reasoning you can see that the multiple of 88 must be greater than the multiple of 42 by 82 so as to satisfy the condition in the question.

880 – 82 ------ 798

So the number is 798 + 1 ------ 799

Best wishes

[Michaelia0816]

tianzhu:

Michaelia0816:

Pls help with this question,

1) A number has 3 digits. When it is divided by 6 or 7, it leaves a remainder of 1. When it is divided by 8 or 11, it leaves a remainder of 7. What is the largest such number?

Hi

You may use “SL” to do this question.

Find multiples of 42 + 1

Similarly find multiples of 88 + 7

Do a listing, the answer is 799.

I believe you can use your calculator for this question, so with a bit of planning, it’s not too tedious.

Another way, with some reasoning you can see that the multiple of 88 must be greater than the multiple of 42 by 82 so as to satisfy the condition in the question.

880 – 82 ------ 798

So the number is 798 + 1 ------ 799

Best wishes

How do you get it?

[Michaelia0816]

This answer is found on yahoo,



3-digi number divided by 6, remainder = 1
3-digi number divided by 7, remainder = 1

SO,
The 3-digi number divided by (6x7)42, remainder = 1

The largest 3-digit number = 42 x 23=
= 966+1 = 967 ........................................… [1]

Also,
3-digi number divided by 8, remainder = 7
3-digi number divided by 11, remainder = 7

The 3-digi number divided by (8x11)88, remainder = 7

The largest 3-digit number = 88 x 11=

= 968+7 = 975 ........................................… [2]

From [1] and [2].

975-88 = 887-88 = 799 >=====================< ANSWER

How to get 23 and 11?

[tianzhu]

Michaelia0816:

2) A rectangle of length 24 cm is given as shown below. Twelve identical isoceles triangles are cut from it. The perimeter of the remaining figure is 120 cm more than that of the rectangle. Find the perimeter of an isoceles triangle?

Picture of the figure for Q2:
http://t.co/lUBjqv11

Hi

Where is this question from?

Let the base of the isosceles triangle be b and each slanting side be s.

b ------ 24/6 ------ 4

24s -------- 120 + 48 ------- 168

s ----- 7

Perimeter of an isosceles triangle -------- 7+7+4 ------ 18

Best wishes