Tutor MathsGuru: Ask me for your burning Maths questions!

[blessedami]

hljthjrh:

super star:

Is the ans 8:35am[quote=\"blessedami\"]
Is the answer 8.35 am?

Yes the answer is835 am. How do u interpret the question? U took 9am as the time on Peter's watch ?[/quote]Hi,

My DS interpreted it like that because according to the question Peter reached \"on time \" and that time is 9 am, \"according to his watch\".

Since his watch is 15 minutes fast, the actual time is only 8.45 am. Ali reached earlier by 10 mins, which is 8.35 am.

[blessedami]

super star:

pls hlep me with this problem

Aaron and kumar took part in a 24km marathon.Aaron ran half the distance at a speed of 10km/h and jogged the rest of the way at a speed of 8 km/h.kumar ran half of his total time at 12 km/h and jogged the rest of the time at 6 km/h. If they started the marathon at 8 am ,at what time would each of them finish?

Since Aaron ran half the distance at 10km/h and the other half at 8 km/h;

12km÷10km/h= 1 1/5 h= 1 h 12 min
12km÷8km/h=11/2 h = 1 h 30 min
Total time taken by Aaron is 2 h 50 min
He will finish at 10. 50 am

For Kumar, he ran half of his time at 12 km/h and the other half at 6 km/h
1/2 t x 12 km/h + 1/2 t x 6 km/h = 24 km
1/2 t x 18 km/ h = 24 km
1/2 t = 24 km ÷ 18 km/h = 1 h 20 min
t= 1h 20 min x 2 = 2 h 40 m
So, he will finish at 10. 40 am

[Almighty]

super star:

please help me with these problems


(ii)How many cubes of side 2cm can be fitted into Box A of dimension 12cm by 5 cm by 7cm? my ans is 52...the ans key says 36.which is correct. pls explain

Hi Superstar,

No. of cubes in the length -------12/2= 6\t\t\t
\t\t\t\t\t\t
No. of cubes in breadth --------- 5/2 = 2.5 (Which means only 2 cubes can be fitted)\t\t\t\t\t\t\t\t\t\t
No. of cubes in height ---------- 7/2 = 3.5 (Which means only 3 cubes can be fitted )\t\t\t\t\t\t\t\t\t\t\t
No of cubes = 6 X 2 X 3\t\t\t\t\t\t\t\t\t
= 36.

[Tang]

blessedami:

starlight1968sg:

[quote=\"Tang\"] Hi,


A - largest, E - smallest

A + B = 139

A + C = 137

Based on answer above C = 62, so A = 137 - 62 = 75

and B = 139 - 75 = 64


E + D = 105

E + C = 113

Similarly, E = 113 - 62 = 51 and D = 105 - 51 = 54

A, B, C, D, E --> 75, 64, 62, 54, 51

However the mass of 2 are:

139, 137, 129, 126, 126, 118, 116, 115, 113 and 105

These do not tally with those numbers given in the question.

Any comments?

I don't understand that given solution too.

Hi,

My DS worked it out like this:

Let the boys in the order of lightest to heaviest be v,w,x,y,z

The weight of the two lightest boys, v and w is 105

So,
v+w=105 )
v+x=113 )

2 v + w + x = 105 + 113 = 218
2 v = 218 - 118 = 100
v = 100/2 = 50

v+y=115
v+z=116

So w = 105 - 50 = 55, x = 113 - 50 = 63, y = 115 - 50 = 65, z = 116 - 50 = 66


w+x=118 w + x = 55 + 63 = 118 OK
w+y=124 w + y = 55 + 65 = 120 Don't tally!
w+z=125 w + z = 55 + 66 = 121 Don't tally!

x+y=130 x + y = 63 + 65 = 128 Don't tally!
x+z=137 x + z = 63 + 66 = 129 Dpn't tally!

y+z=139 y + z = 65 + 66 = 131 Don't tally!

So in total there would be four v, four w, four x, four y and four z.

Total weight would be 1224kg
So, 4(v+w+x+y+z) --> 1224kg
v+w+x+y+z--> 1224kg/4= 306 kg

Since the two lightest weigh 105 kg and the two heaviest weigh 139 kg, the third heaviest or the last boy weighs, 306 kg- 139 kg- 105 kg= 62 kg[/i][/quote]
Hi,

See comments underlined.

[beauty queen]

Mrs Sitoh has just enough flour to bake either 12p muffins or 9r pies. If she has already baked 40 muffins and 3r pies how many more muffins can she still bake?



please help

[Almighty]

blessedami:

super star:

pls hlep me with this problem

Aaron and kumar took part in a 24km marathon.Aaron ran half the distance at a speed of 10km/h and jogged the rest of the way at a speed of 8 km/h.kumar ran half of his total time at 12 km/h and jogged the rest of the time at 6 km/h. If they started the marathon at 8 am ,at what time would each of them finish?

Since Aaron ran half the distance at 10km/h and the other half at 8 km/h;

12km÷10km/h= 1 1/5 h= 1 h 12 min
12km÷8km/h=11/2 h = 1 h 30 min
Total time taken by Aaron is 2 h 50 min
He will finish at 10. 50 am

For Kumar, he ran half of his time at 12 km/h and the other half at 6 km/h
1/2 t x 12 km/h + 1/2 t x 6 km/h = 24 km
1/2 t x 18 km/ h = 24 km
1/2 t = 24 km ÷ 18 km/h = 1 h 20 min
t= 1h 20 min x 2 = 2 h 40 m
So, he will finish at 10. 40 am

Hi blessedami,
Please see your answer marked in red by me.I think there is a calcualtion error.Accordingly,
Total time taken = 1h 30 min + 1 h 12 mins = 2h 42 min
He will finfish at 10.42 am.

[super star]

thank you verymuch

livewith_vanilla:

Adrian and bob started driving at the same time. bob took 6hrs to complete his journey while adrian took 9hrs to complete his.After 3 hrs ,the 2 men were left with the same distance to complete.what is the ratio of the distance of bob's journey to the distance of adrian's journey.?



-

Bob will complete 1/6 of his journey in one hour
Adrian will complete 1/9 of his journey in one hour

Three hours:

Bob will complete 3/6 of his journey
Adrian will complete 3/9 of his journey

That leaves Bob with 3/6 of his journey to complete and Adrian with 6/9 of his journey.

3/6B=6/9A
1/2B=2/3A

Bob->4u
Adrian->3u

B:A
4:3

Not sure if correct

[Almighty]

beauty queen:

Mrs Sitoh has just enough flour to bake either 12p muffins or 9r pies. If she has already baked 40 muffins and 3r pies how many more muffins can she still bake?


please help

Hi beauty queen,
Let me try,

12 p = 9r
4 p = 3r
so, Amt of flour left is 12p - 4p = 8p
Therefore,muffins she can still bake = 8 p - 40
8(p-5)
Right??

[Almighty]

Dharma:

Almighty:

[quote=\"Dharma\"]
Hi Almighty,

Frankly, I find the question not clear enough. You may have gotten it from an assessment book or a school exam paper. Not to worry to much, in PSLE, the questions are checked very carefully by a panel and there is a very minimal chance of ambiguity. My advice is for maths, just use the direct interpretation. Normally it is not the intention of the setter to test your language ability.

[/quote]Seriously hope so Sir!! Thankyou for your reply.

[super star]

thank you very much

almighty is correct with the first part of the problem

blessedami:

super star:

pls hlep me with this problem
Aaron and kumar took part in a 24km marathon.Aaron ran half the distance at a speed of 10km/h and jogged the rest of the way at a speed of 8 km/h.kumar ran half of his total time at 12 km/h and jogged the rest of the time at 6 km/h. If they started the marathon at 8 am ,at what time would each of them finish?

Since Aaron ran half the distance at 10km/h and the other half at 8 km/h;

12km÷10km/h= 1 1/5 h= 1 h 12 min
12km÷8km/h=11/2 h = 1 h 30 min
Total time taken by Aaron is 2 h 50 min
He will finish at 10. 50 am

For Kumar, he ran half of his time at 12 km/h and the other half at 6 km/h
1/2 t x 12 km/h + 1/2 t x 6 km/h = 24 km
1/2 t x 18 km/ h = 24 km
1/2 t = 24 km ÷ 18 km/h = 1 h 20 min
t= 1h 20 min x 2 = 2 h 40 m
So, he will finish at 10. 40 am