Tutor MathsGuru: Ask me for your burning Maths questions!

[Herbie]

Hi Uncle Dharma


Can explain why 1B - 1P = $1???

Many thanks!

[Dharma]

Herbie:

Hi Uncle Dharma


Can explain why 1B - 1P = $1???

Many thanks!

Hi Herbie,

If you buy 1 extra book you need $0.40 more but if you buy 1 extra pencil you have $0.60 left.

So, difference in price of 1 book and 1 pencil is $ 0.40 + $0.60 = $1.00

[Herbie]

Hi Uncle Dharma,


Thanks for yr explanation!

[Dharma]

Vanilla Cake:

YLH88:

Hi,

From Observer's solution, I'm still abit confused on how the following steps are derived :

a) why need to add 4 to 8035 ?

2003 - 1981 = 22 years
22/4 = 5 leap years (max)
22 x 365 + 5 =8035 days
8035 + 4 = 8039 --> ??
8039/7 = 1148 r 3

ans : It was 3.

b) why need to add 4 to 25 x 365 + 6 ?

2006 - 1981 = 25 years
25/4 = 6 leap years (max)
25 x 365 + 6 + 4 = 9135 --> ??
9135/7 = 1305 or 1304 r 7

ans : It was 7.

c) why need to add 7 + 4 to 31 x 365 + 31 + 7 + 4 ?

2012 - 1981 = 31 years
31/4 = 7 leap years (max)
31 x 365 + 31 + 7 + 4 = 11357 days --> ??
11357/7 = 1622 r 3

3 --> Wednesday

ans : It is Wednesday.

Hi YLH88,
Why don't you voice your query in the http://psle2010a.blogspot.com/2010/09/challenging-p6-2010-sa2-nanyang-p2-q15.html#comments or post your query in the cbox of his blog while waiting for comments from KSP members?
Thanks.

VC mum

Hi YLH88,

My opinion is Vanilla Cake's solution is very clear and easy to understand. It will be good enough if you are able to understand her explanation.

[hamsterss]

Can someone help me with this question?


Jason and Carl cycled from Westpoint to Spring Mall at 11km/h and 8km/h repectively. Jason left Westpoint an hour later than Carl and arrived at Spring Mall 0.5h later than Carl. How long did Jason took?

Thanks

[Vanilla Cake]

hamsterss:

Can someone help me with this question?


Jason and Carl cycled from Westpoint to Spring Mall at 11km/h and 8km/h repectively. Jason left Westpoint an hour later than Carl and arrived at Spring Mall 0.5h later than Carl. How long did Jason took?

Thanks

Hi hamsterss,
I am the mum of VC and are you a parent? Not sure whether the method used is applicable for you or not?

Constant distance concept where speed is inversely proportional to time.

Ratio of speed
Jason : Carl
11 : 8

Ratio of time
Jason : Carl
8 : 11

Difference in time = 1 h - 0.5h = 0.5h
Difference in time in terms of unit = 11u-8u = 3u
3u-> 0.5h
u -> 1/6 of h = 10 min

Time taken by Jason -> 8u = 8x10min = 80 min

VC's mum

[hamsterss]

Vanilla Cake:

hamsterss:

Can someone help me with this question?


Jason and Carl cycled from Westpoint to Spring Mall at 11km/h and 8km/h repectively. Jason left Westpoint an hour later than Carl and arrived at Spring Mall 0.5h later than Carl. How long did Jason took?

Thanks

Hi hamsterss,
I am the mum of VC and are you a parent? Not sure whether the method used is applicable for you or not?

Constant distance concept where speed is inversely proportional to time.

Ratio of speed
Jason : Carl
11 : 8

Ratio of time
Jason : Carl
8 : 11

Difference in time = 1 h - 0.5h = 0.5h
Difference in time in terms of unit = 11u-8u = 3u
3u-> 0.5h
u -> 1/6 of h = 10 min

Time taken by Jason -> 8u = 8x10min = 80 min

VC's mum

Really thanks for your help! Nope,im a student ^o^
I was stuck after this : [quote]Ratio of speed
Jason : Carl
11 : 8

Ratio of time
Jason : Carl
8 : 11[/quote]My teacher just taught us but can't really understand the method >o< Can you explain to me how come the ratio can be exchangable?

[pecalis]

[/quote]

Really thanks for your help! Nope,im a student ^o^
I was stuck after this : [quote]Ratio of speed
Jason : Carl
11 : 8

Ratio of time
Jason : Carl
8 : 11[/quote]My teacher just taught us but can't really understand the method >o< Can you explain to me how come the ratio can be exchangable?[/quote]

Speed = Distance / time
So speed increases, distance increases the same proportion
BUT
When speed increases, the time taken is less by the same ratio.
Ratio of speed of A : Speed of B
= Ratio of distance travelled by A : distance travelled by B

BUT
Time taken by A: time taken by B
= speed of B : speed of A

[CJM]

Hi all,


need ur help on this question : -

Mr Lim sold a total of 96 papayas and watermelons for $560.
He sold each papaya for $3 and each watermelon for $7.
How many watermelons did Mr Lim sell ?

[little_twin_stars]

Hi there…


There is this question:

At 9.20 am, Terence left Town X for Town Y at a constant speed. 1 hour larer, Gary started travelling from Town X on the same road at a constant speed. Gary overtook Terence at 12.20 pm. The speed which Gary was travelling at was 40km/h faster than Terence. Find the speed that Terence was travelling at.

The solution given is as follows:

Time (Terence): Time (Gray) -> 3 : 2
Speed (Terence = D/3
Speed (Gary) = D/2
D/2-D/3 = 1/6 D
1/6 D = 40 km
D = 40km x 6
=240 km/h
Average Speed (T) = 240/3
= 80 km/h


However, I worked it out another way. I would like to know if it is also correct.

Time taked for Gary to overtake Terence -> 2 h
The extra distance that Gary could cover in the 2 h -> 40 x 2
= 80 km
Speed of Terence -> D/T = 80/1
= 80 km/h

Thanks in advance