Q&A - PSLE Math

[Michaelia0816]

Thx, do help with the post I posted just now too

[tianzhu]

Winx5015:

(3). Ali and Ben had $150.30 at first. Ali gave 1/2 of his money to Ben. Ben then gave 2/5 of the total he had to Ali. In the end, each of them had the same amount of money. How much did each boy have at first?

Hi

Your Q3 is quite similar to this question.

Hope this helps.

Best wishes

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[Michaelia0816]

Tianzhu, Can I have the picture of the guess and check or give me a clue, it my HW

[Michaelia0816]

I not sure about the guess and check, I cannot do it

[tianzhu]

Michaelia0816:

Tianzhu, Can I have the picture of the guess and check or give me a clue, it my HW

Hi girl

Tomorrow, I’ll PM to you.

Best wishes

[Michaelia0816]

Ok!

[MathIzzzFun]

Michaelia0816:

Pls try not to use algebra, I am easily confused. Help with this Qn,


Motorist takes 1/2 h less than the usual time to travel from Town K to Town J when he increases his average speed by 10%. For a distance of 100km, he will take 1/3 h less than the usual time if his speed is 20% more than the average speed from Town K to Town J. Find the distance between Town K and Town J.

For a distance of 100km, he will take 1/3 h less than the usual time if his speed is 20% more than the average speed from Town K to Town J. - info provided in this sentence can be used to calculate the normal speed:

normal speed : 120% normal speed = 100 : 120 = 10 : 12
Time ratio to travel 100km at normal speed : 120% normal speed = 12u : 10u
2u --> 1/3h
12u --> 2h ie it takes 2h to cover 100 km at normal speed, so normal speed = 100km/2h = 50 km/h

Time to travel from town K to town J at
normal speed : 110% normal speed = 110 : 100 --> 11u : 10u
1u --> 1/2h (since it takes 1/2 h less to travel at 110% normal speed)
11u --> 5.5h, distance between town K and town J = 5.5h x 50 km/h = 275 km

cheers.

[Michaelia0816]

Pls help with this question,


A car travels from town P to town Q at a constant speed. When it increases its speed by 20%, the journey from P to Q takes 1 hour less than its usual time. When it travels at its usual speed for 100 km before increasing its speed by 30%, the journey also takes 1 hour less than usual. Find the distance between the two towns.

[Michaelia0816]

MathIzzzFun:

Michaelia0816:

Pls try not to use algebra, I am easily confused. Help with this Qn,


Motorist takes 1/2 h less than the usual time to travel from Town K to Town J when he increases his average speed by 10%. For a distance of 100km, he will take 1/3 h less than the usual time if his speed is 20% more than the average speed from Town K to Town J. Find the distance between Town K and Town J.

For a distance of 100km, he will take 1/3 h less than the usual time if his speed is 20% more than the average speed from Town K to Town J. - info provided in this sentence can be used to calculate the normal speed:

normal speed : 120% normal speed = 100 : 120 = 10 : 12
Time ratio to travel 100km at normal speed : 120% normal speed = 12u : 10u
2u --> 1/3h
12u --> 2h ie it takes 2h to cover 100 km at normal speed, so normal speed = 100km/2h = 50 km/h

Time to travel from town K to town J at
normal speed : 110% normal speed = 110 : 100 --> 11u : 10u
1u --> 1/2h (since it takes 1/2 h less to travel at 110% normal speed)
11u --> 5.5h, distance between town K and town J = 5.5h x 50 km/h = 275 km

cheers.

Why it is 2u? Sorry, actually I bit stupid, I am a bit slow in learning, especially in math.

[tianzhu]

Michaelia0816:

Pls help with this question,


A car travels from town P to town Q at a constant speed. When it increases its speed by 20%, the journey from P to Q takes 1 hour less than its usual time. When it travels at its usual speed for 100 km before increasing its speed by 30%, the journey also takes 1 hour less than usual. Find the distance between the two towns.

Hi

I don’t think this is a typical PSLE type of question.

Usual speed: New speed ----- 10:12 ------5:6

Usual time: New time -------6:5

1 unit ----- 1h

Usual time ------6 h

Now consider the second scenario.

Usual speed: New speed ----- 10:13

Usual time: New time -------13:10

3 units ------ 1

13 units ------ 13/3 or 4 1/3

6 – 4 1/3 ------ 1 2/3 (5/3)

5/3 ----- 100 km

6 ------ 100*6/5/3 ------- 360km

Best wishes