Q&A - PSLE Math

[Michaelia0816]

60.

[tianzhu]

Michaelia0816:

the ratio of a van's speed to that of a car's speed was 3:5. If the van took 1 minutes more to cover a distance of 0.5 km than the car, find the speed of the van in km/h. ( hint: first convert 0.5 km/min to km/h)

Hi

1 min ------- 0.5 km
60 mins -------- 30 km

2 units ------- 30
1 unit ------ 15

Speed of van ------- 3 units ------- 15*3 ----45km/h

Best wishes

[tianzhu]

Michaelia0816:

tianzhu:

[quote=\"Michaelia0816\"]4) Town J and Town K were 450km apart. Nancy started to drive from Town J for Town K at 10am. At hour later, Jenny started to drive from Town K for Town J at 75% the average speed of Nancy. they met each other at 1pm along the way.

A) at what speed was nancy driving?
b) How far from Town J did they met each other?

Hi

Start with a simple diagram.

In 1h, Nancy covered 4 units.
In 1h, Jenny covered 3 units.

From 10 am to 11 am, Nancy covered 4 units.

From 11 am to 1 pm, Nancy covered 8 units and Jenny covered 6 units

Total units ------- 18 units
450/18 ------25

4 units ------ 4*25 ------ 100 km/h (Nancy’s speed)

They met at 100+200 or 300 km away from J.

Best wishes

How to find it? Is it 8u---200?[/quote]Hi

Yes.

Best wishes

[tianzhu]

tianzhu:

Michaelia0816:

Roger took 1/1/3 h to drive from Greenland to pinkcity at an average speedof 0km/h. After this, he increased his speed by 25% and continued driving to redsville for 40 minutes.

A) how far did Roger drive together?
B) find his average speed for the whole journey?

Hi

Please check.

Best wishes

Hi

Please check.

Speed is 0?

Best wishes

[tianzhu]

Michaelia0816:

Yes, I confirm, sorry Tianzhu it should be point p to point r and point s to point q! for question 9.

Hi

Any diagram provided in the question?

Best wishes

[Michaelia0816]

tianzhu:

tianzhu:

[quote=\"Michaelia0816\"]Roger took 1/1/3 h to drive from Greenland to pinkcity at an average speedof 0km/h. After this, he increased his speed by 25% and continued driving to redsville for 40 minutes.

A) how far did Roger drive together?
B) find his average speed for the whole journey?

Hi

Please check.

Best wishes

Hi

Please check.

Speed is 0?

Best wishes[/quote]It should be 60 instead!

[Michaelia0816]

If Tianzhu,

I got a another question again
Also having difficulties to complete it!
Do the part b one only, I have solved the first one!

Amy and Cindy set off from Town X for Town Y at 1pm., at the uniform speeds of 70km/h and 85km/h respectively?
A) how long did it take for them to be 45km apart? The answer is 3h!
I’d Amy arrived in Town Y at 5.15pm, at what time would Cindy arrived there?

[Michaelia0816]

Still got 17 question!!

[tianzhu]

Michaelia0816:

If Tianzhu,

I got a another question again
Also having difficulties to complete it!
Do the part b one only, I have solved the first one!

Amy and Cindy set off from Town X for Town Y at 1pm., at the uniform speeds of 70km/h and 85km/h respectively?
A) how long did it take for them to be 45km apart? The answer is 3h!
I'd Amy arrived in Town Y at 5.15pm, at what time would Cindy arrived there?

Hi

Use inverse ratio

Speed
Amy:Cindy -------- 70:85 ------- 14:17

Time
Amy:Cindy -------- 70:85 ------- 17:14

17 units ------- 255 minutes
14 units -------- 14*15 -------- 210 minutes ------- 3.5h

3.5h from 1 pm --------- 4.30 pm.

Best wishes

[tianzhu]

Michaelia0816:

Roger took 1/1/3 h to drive from Greenland to pinkcity at an average speedof 60km/h. After this, he increased his speed by 25% and continued driving to redsville for 40 minutes.

A) how far did Roger drive together?
B) find his average speed for the whole journey?

Hi

From GL to PC

60*4/3 ------ 80 km

Increased speed -------- 60*1.25 ------- 75

Distance from PC to R ------ 75*2/3 ------ 50 km

Roger covered (80+50) --------- 130 km

Time taken ------- 4/3 + 2/3 ------ 2h

Average speed -------- 130/2 ------- 65 km/h

Best wishes