Q&A - PSLE Math

[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

[Winx5015]

Hi MathIzzzFun,


Thanks for your help