Tutor MathsGuru: Ask me for your burning Maths questions!

[livewith_vanilla]

Ngserene617:

mathsguru:

Original Title: Let MathsGuru Answer Your Burning Maths Questions!


:welcome:

Dear Parents,

Are you frustrated/stuck when helping your child solve his/her Maths questions? Are you inclined to use Algebra most of the time? Do you have difficulty trying to use diagrams or other heuristic methods (that Primary School students learn) to solve?

:idea: Post your questions here and see how MathsGuru solve them to the best of her ability. Detailed solutions will be posted back in this thread.


Hi MathsGuru,

kindly assist me in this question:
1. Samy spent 2/5 of his money on a toy car and 1/6 of the remaining money on a storybook.
a) What fraction of his money had he left?
b) If he had $40 left, how much had he at first ?

So start asking and watch this space!!

Cheers :celebrate: ,
MathsGuru

P/S (Disclaimer, in case you're wondering...):
Although MathsGuru is a full-time Maths tutor, this thread is meant to be an absolutely free resource for parents (or even children) with no strings attached. Just someone who's passionate about Maths and wanna spread the fun in learning Maths with others.

Hi MathsGuru,

kindly assist me in this question:
1. Samy spent 2/5 of his money on a toy car and 1/6 of the remaining money on a storybook.
a) What fraction of his money had he left?
b) If he had $40 left, how much had he at first ?


I take that this is your question?

My solution:

a)1-1/6=5/6

That means Sam had 5/6 of the remainder left.

1-2/5=3/5

3/5 is the remainder.

Hence,

5/6x3/5=1/2

Ans:1/2

b)

1/2 of the money= $40

Thus,

$40x2=$80

Ans:$80

[Dharma]

super star:

please help me with this problem

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.?

Time ratio => Bob : Adrian = 1 : 2
Speed ratio => Bob : Adrian = 2 : 1

Distance ratio => Bob : Adrian = (2 x 6) : (1 x 9) = 4 : 3

[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?

[super star]

thanks dharma pls explain how you got the time ratio as 1:2

Dharma:

super star:

please help me with this problem

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.?

Time ratio => Bob : Adrian = 1 : 2
Speed ratio => Bob : Adrian = 2 : 1

Distance ratio => Bob : Adrian = (2 x 6) : (1 x 9) = 4 : 3

[hljthjrh]

super star:

Is the ans 8:35am

blessedami:

[quote=\"hljthjrh\"]
No, the answer is not 8.50am. My answer is also different from the teacher's. Posted here to find out how others interpret the question.

Is the answer 8.35 am?

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

[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