Tutor MathsGuru: Ask me for your burning Maths questions!

[mathsguru]

YLH88:

Hi Mathsguru,


Need your help with the below questions :

1) Doran had 8/11 of the number of game cards Thomas had. After Thomas lost 18 cards to Doran, they both had the same number of cards.

a) How many more game cards did Thomas have than Doran at first ?
b) As the game continued, Doran won more cards from Thomas. How many more cards did Thomas lose to Doran such that Doran has 3 times as many cards as him ?

I'm able to get the answer for (a), which is 36. But can't find for (b)

Thank you!

Hi YLH88,

Here's my solution for your reference!


MathsGuru

http://www.postimage.org/image.php?v=Pq8XJWS

[mathsguru]

Emelyn:

I have one question :


Mr Tay bought a massage chair for $888. He sold it to Mr Yeo for $850. He later bought the massage chair back from Mr Yeo for $900 and sold it to Mrs Tan for $1000. How much did Mr Tayy gain ?


MTIA !

Hi Emelyn,

Please take a look at my solution. A quick & dirty way (but surely correct way) is to use what accountants would term as debit and credit.

Of course, this may be too difficult for lower primary students to understand. You can explain it as money forked out vs. money received. The difference will be the gain/loss depending on which amount is bigger.

Hope this helps!


MathsGuru

http://www.postimage.org/image.php?v=Pq8_Pv0

[firebird]

Dear Mathsguru


Thank you very much for the sloution given.

The question 1 was typed wrongly by me. I am very sorry for the error.

The question should have been:

Victor wants to travel from Town X to Town Y. If he drives at an average speed of 60Km/h, he would reach Town Y at 10.30am. If he drives at an average speed of 80 Km/h, he would reach Town Y at 9.45am.

a) Find the distance between Town X and Town Y.

b) At what average speed should he drive if he wants to reach Town Y at 9.30am?

Many thanks
firebird

[Dharma]

firebird:

Dear Mathsguru


Thank you very much for the sloution given.

The question 1 was typed wrongly by me. I am very sorry for the error.

The question should have been:

Victor wants to travel from Town X to Town Y. If he drives at an average speed of 60Km/h, he would reach Town Y at 10.30am. If he drives at an average speed of 80 Km/h, he would reach Town Y at 9.45am.

a) Find the distance between Town X and Town Y.

b) At what average speed should he drive if he wants to reach Town Y at 9.30am?

Many thanks
firebird

Hi firebird,

Use ratios to solve easily.

(a)\tSpeed ratio = 3 : 4
Time ratio = 4 : 3 (For fixed distance)
4u – 3u = 3/4hrs
1u = ¾ hrs

Distance between Town X and Town Y = Speed x Time = (60) x (4 x ¾) = 180 (180km)

(b)\tVictor leaves Town X at 7.30 am (3 hrs before 10.30am)
If wants to reach Town Y at 9.30am,

Average speed = 180/2 = 90 (90km/h)

[Emelyn]

mathsguru:

Hi Emelyn,


Please take a look at my solution. A quick & dirty way (but surely correct way) is to use what accountants would term as debit and credit.

Of course, this may be too difficult for lower primary students to understand. You can explain it as money forked out vs. money received. The difference will be the gain/loss depending on which amount is bigger.

Hope this helps!


MathsGuru

http://www.postimage.org/image.php?v=Pq8_Pv0

Thanks Mathsguru and EVERYONE who responded.

Like CoffeeCat, we (5 of us in the office working on the qn) were very disturbed with :

900 - 850 = 50.

which is also what the 2 school teachers of my colliq's dd1 and dd2 did.

For a moment, we were wondering is this a new way of calculating, is this a trick qn, and why we cannot solve a P3 question !!!!

Phew.... thanks for giving our self-confidence back....

[firebird]

Good morning Mathsguru


Please help me on the following P6 maths:

1) Clement had a wooden block measuring 50cm by 70cm by 90cm.
He wanted to cut out some little cuboids measuring 2cm by 3cm by 4cm.
What is the minimum amount of wood wasted?

Given answer is 360cm cuboids. I am getting 180 cuboids. Please help.

2) Micheal asked his classmate what time it was.
Jackson, the math whiz, replied with a cheeky grin,
"It’s 2000 hours, 1990 minutes and 1980 seconds before midnight?
Can you help Micheal find out what time it is?

I am totally lost.

Thank you
firebird

[firebird]

Good morning Dharma


Many thanks
firebird

[CoffeeCat]

firebird:

Good morning Mathsguru


Please help me on the following P6 maths:

1) Clement had a wooden block measuring 50cm by 70cm by 90cm.
He wanted to cut out some little cuboids measuring 2cm by 3cm by 4cm.
What is the minimum amount of wood wasted?

Given answer is 360cm cuboids. I am getting 180 cuboids. Please help.

2) Micheal asked his classmate what time it was.
Jackson, the math whiz, replied with a cheeky grin,
\"It's 2000 hours, 1990 minutes and 1980 seconds before midnight?
Can you help Micheal find out what time it is?

I am totally lost.

Thank you
firebird

edited : my first try wrong look at newer post.

[Dharma]

firebird:

2) Micheal asked his classmate what time it was.
Jackson, the math whiz, replied with a cheeky grin,
\"It's 2000 hours, 1990 minutes and 1980 seconds before midnight?
Can you help Micheal find out what time it is?

I am totally lost.

Thank you
firebird

2000 hrs + 1990 mins + 1980 sec
= 2000 + (1990 x 60 + 1980)/3600
= (2000 + 33 + 43/60) hrs
= (1992 + 8 + 24 + 9 + 43/60)hrs
= 84 days + 17hrs + 43/60 hrs

To find out time …. 17 hrs and 43 mins before midnight i.e. 6.17am

[firebird]

Dear coffeeCat & Dharma


Thanks for your reply.

The question one answer given by coffeecat is not as the same as the given answer - i.e. 360 cm3. I really do not know!

The question two answer given by Dharma is same as given answer - i.e 6.17am. However, I could not understand the working.

Regards
firebird