Q&A - PSLE Math

[tianzhu]

Hi, small


I guess you just wanted to check the answer. It is $69.60.
1 kg of beef ----- 7.2
1 kg of venison -----12

[Muffins]

small,


venison beef working:
$8.64 = 120% 1kg beef
$8.64 divided by 120% equals $7.20 which is 1kg of beef
$7.20 multiplied by 2 = $14.40 which is 120% of 1kg venison
$14.40 divide by 120% = $12
$12 multiplied by 4 = $48
$7.20 multiplied by 3 = $21.60

$48 + $21.60 = $69.60

Hope my ans. is correct!

[Dharma]

tianzhu:

Hi, small


I guess you just wanted to check the answer. It is $69.60.
1 kg of beef ----- 7.2
1 kg of venison -----12

Hi Tianzhu,

Got a different answer .... is it something to do with the \"120% more\"?

120% - $8.64
100% - $7.20 (1kg of beef)

220% - $14.40 (2kg of beef)
100% - $ 6.55 (1kg of venison)

4kg venison + 3 kg beef = 4x$6.55 + 3x$7.20 = $47.80 ($47.78 if use calculator)

[tianzhu]

Hi Dharma


Thanks for the correction.I made a mistake.(use 20% more instead of 120% more)
Price of venision per kg should be $6.55.
Price of beef per kg is $7.20.
Best wishes.

Hi small
Please consider my earlier post as null and void.
The answer is $47.80.
Best wishes

[Muffins]

Hi Dharma and Tianzhu,


The answer I got was also $69.60!

Could you pls show me how the answer is $47.80 (or $47.78 ) and why my answer is wrong? :?

Thanks in advance.

Muffins.

[Full.010894Cream]

Muffins:

Hi Dharma and Tianzhu,


The answer I got was also $69.60!

Could you pls show me how the answer is $47.80 (or $47.78 ) and why my answer is wrong? :?

Thanks in advance.

Muffins.

Dharma:

Hi Tianzhu,

Got a different answer .... is it something to do with the \"120% more\"?

120% - $8.64
100% - $7.20 (1kg of beef)

220% - $14.40 (2kg of beef)
100% - $ 6.55 (1kg of venison)

4kg venison + 3 kg beef = 4x$6.55 + 3x$7.20 = $47.80 ($47.78 if use calculator)

[Muffins]

Oh, thanks Dharma, you're really smart, I also got confused with the 20% 120% thing! THANKS!


Muffins

[Dharma]

janice099:

Hello there, this is my first reply. Thanks for helping


John can walk to school in 40 minutes while his brother, Jack, takes 20 minutes. If they both start walking to school at the same time, how long will it take for John to be 2/5 as far as Jack.

For a fixed distance

Time ratio of John to Jack is 2:1
Speed ratio of John to Jack will be 1:2

For a fixed time;

Distance ratio of John to Jack will be 1 : 2 same as the speed ratio.

Can’t understand how the distance ratio be 2:5?

[alamak]

[Moderator's note: Topics merged.]


A car and a coach travelled from Town A to Town B. The coach left Town A at 0648 and it took 5 hours to reach Town B. The car started 30 minutes later than the coach and it took 4 hours to reach Town B. At what time did the car catch up with the coach? :?:

[Vanilla Cake]

A car and a coach travelled from Town A to Town B. The coach left Town A at 0648 and it took 5 hours to reach Town B. The car started 30 minutes later than the coach and it took 4 hours to reach Town B. At what time did the car catch up with the coach?


Information from question
(1) Both car and coach travelled the same distance from Town A to Town B meaning that distance in this case was constant.
(2) The car started 1/2 hour later and took less time than the coach to reach Town B meaning that the car travelled faster than the coach.
(3) Duration of journey for the car was 4 hours and for the coach was 5 hours.

Solution
Find the 1st common multiple of 4 and 5 and you will get 20.
This was the distance between both Towns A and B which was 20 units.

Coach took 5 hours to travel 20 units
Coach took 1 hour to travel 4 units

Car took 4 hours to travel 20 units
Car took 1 hour to travel 5 units

But the coach started 1/2 hour earlier and had travelled:
(1/2 x 4) units = 2 units.
So, the car had to catch up for this \"2 units\" of the distance.

From above, car could travel faster than the coach :
Difference in 1 hour = (5-4)units = 1 unit.
This means that for 1 hour, the car could catch up by 1 unit.
For 2 units, the car would require 2 hours.

0648.......30 min..0718..........2 hours .........0918

Hence, the car caught up with the coach at 0918 h