Q&A - PSLE Math

[tianzhu]

superworried mum:

Hi, need help in this question,


I have some red and blue ribbons in a bottle.
If i add in 20 red ribbons, 60% of my ribbons are blue.
If i add in another 60 blue ribbons, 75% of mu ribbons are blue.
How many ribbons have I in the bottle?

Can there be two answers for this?
Thanks

Hi

This question has been discussed in forums regularly.

Depending on one’s interpretation of the word another in the second condition, one may end up with 180 or 80.

It’ll be helpful if current PSLE students or their parents help to clarify with their school teachers on this question.

Best wishes

[Michaelia0816]

Someone help pls? A motorist took 3 h to travel from town A to town B. His average speed for the whole journey was 80 km/h. For the first 1/4 of the journey, he travelled at an average speed of 60km / h. Find his average speed for his remaining journey.

[tianzhu]

Michaelia0816:

Someone help pls? A motorist took 3 h to travel from town A to town B. His average speed for the whole journey was 80 km/h. For the first 1/4 of the journey, he travelled at an average speed of 60km / h. Find his average speed for his remaining journey.

Hi

Distance between Town A and B ------ 3*80 ------ 240 km

Distance covered in first quarter ------ 60 km

Time taken ------ 60/60 ------ 1h

240 – 60 ------ 180
180/2 -------- 90

Average speed for remaining journey ------ 90 km/h

Best wishes

[Chan09]

Need some help:

1) p had 80 pieces of $10 notes and $50 notes. He used 1/2 of the $10 notes and withdrew another 4 piecescof $50 notes from bank. Aftervwhich the no. of $50 notes he had was 2/5 the no. Of $10 notes. Find the total value ofvthe 80 pieces of notes he had at first? Ans : $1200 as want to use model to solve.

2) there are 480 people in Gp X and 20% are children. Of the 280 people in Gp Y, 70% are children. Some people moved from Gp Y to Gp X . At the end the no. of children in Gp Y and X are 50% and 40% respectively. How many people moved from Y to X?

Thank you.

[tianzhu]

Chan09:

Need some help:

1) p had 80 pieces of $10 notes and $50 notes. He used 1/2 of the $10 notes and withdrew another 4 piecescof $50 notes from bank. Aftervwhich the no. of $50 notes he had was 2/5 the no. Of $10 notes. Find the total value ofvthe 80 pieces of notes he had at first? Ans : $1200 as want to use model to solve.

2) there are 480 people in Gp X and 20% are children. Of the 280 people in Gp Y, 70% are children. Some people moved from Gp Y to Gp X . At the end the no. of children in Gp Y and X are 50% and 40% respectively. How many people moved from Y to X?

Thank you.

Hi

For Q1,start with MD in the after scenario.

$10 ------ 5 boxes (units)
$50 ------ 2 boxes (units)

Note that he withdrew another 4 pieces of $50 notes from the bank, so that’s “fresh fund” or injection of fund to existing holdings.

At first

$10 ------ 10 boxes (units)
$50 ------ 2 boxes – 4

12 units ------ 80+4 ------84

1 unit ----- 7

$10 ------ 70*10 ----- 700
$50 ------ 10*50 ----- 500

Total value@first ------ 1200

For Q2,please check the question against your source.

Is this question worded exactly as the original?

Did you make any changes to it?

Best wishes

[Winx5015]

Hi, need help for this question.


Q1). Mr Siva sold a number of similar pens. He sold 75% of them at $8 each and the rest at a discount of 50%. He collected $2800 from the sales of these pens.
(a). What was the price of 1 pen after the discount? - Ans: $4
(b). How many pens did Mr Siva sell at $8 each?

Got problem in getting the answer for (b). Pse help!

thanks.

[MathIzzzFun]

Winx5015:

Hi, need help for this question.


Q1). Mr Siva sold a number of similar pens. He sold 75% of them at $8 each and the rest at a discount of 50%. He collected $2800 from the sales of these pens.
(a). What was the price of 1 pen after the discount? - Ans: $4
(b). How many pens did Mr Siva sell at $8 each?

Got problem in getting the answer for (b). Pse help!

thanks.

Hi

number of pens@$8 : pens@$4 = 3u : 1u
Total sales collected = 3u x 8 + 1u x 4 =28u
28u --> 2800, 1u = 100
Pens@$8 --> 300

cheers.

[Chan09]

Hi tianzhu,


This was the question given bybteacher as it is:
2) there are 480 people in Gp X and 20% are children. Of the 280 people in Gp Y, 70% are children. Some people moved from Gp Y to Gp X . At the end the no. of children in Gp Y and X are 50% and 40% respectively. How many people moved from Y to X?

Not sure if this can be solved?

[jarenchuatw]

A snail tried to crawl out from the bottom of a well. For every 4cm that it crawled, it slipped back by 1cm. It took 4 seconds to crawl 1cm, and 2 seconds to slip back.

(a) What was the height the snail climb in 2 minutes?
(b) What was the shortest time needed for the snail to climb 56cm?

[tianzhu]

Chan09:

Hi tianzhu,


This was the question given bybteacher as it is:
2) there are 480 people in Gp X and 20% are children. Of the 280 people in Gp Y, 70% are children. Some people moved from Gp Y to Gp X . At the end the no. of children in Gp Y and X are 50% and 40% respectively. How many people moved from Y to X?

Not sure if this can be solved?

Hi

Please check with the teacher.

If 280 is changed to 380,it's solvable.

Best wishes