Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

leesf:

Hi Mathsguru,


I have a question.

A & B share some beads. If A gives B 1/3 of his share, B would have 70 beads more than A. If A gives B 1/5 of his share, B would ahve 10 beads more than A. How many beads do A have at first?

Thanks

If A gives B 1/3 of his share
At last
A : 15units – 5 unit = 10 units
B : 10 units + 70

At first
A : 15 units
B : 10 units + 70 – 5 unit = 5 units + 70

If A gives B 1/5 of his share
At last
A = 15units – 3 units = 12 units
B = 12 units + 10

At first
A : 15 units = 225
B = 12 units + 10 – 3 units = 9 units + 10

The no. of beads that A or B had at first must be the same for both the conditions.

5 units + 70 = 9 units + 10
4 units = 60
1 unit = 15

No. of beads that A had at first = 15 x 15 = 225

[cafelatte]

Need to know the step-by-step thinking procedure for solution this question :


When one of the following numbers is excluded, the sum of the remaining numbers is divisible by 2,3 and 5. What is the number?
29,28,32,45,29,47,17,11?

[Dharma]

cafelatte:

Need to know the step-by-step thinking procedure for solution this question :


When one of the following numbers is excluded, the sum of the remaining numbers is divisible by 2,3 and 5. What is the number?
29,28,32,45,29,47,17,11?

1.\tTo divide by 2 – the ones digit must be an even number
2.\tTo divide by 3 – the sum of digits must be divisible by 3
3.\tTo divide by 5 – the ones digit must be either 0 or 5

Therefore the number must have ones digit that is 0 and the sum of digits must be divisible by 3.

Adding up the ones digits of the 8 numbers given
9 + 8 + 2 + 5 + 9 + 7 + 7 + 1 = 48

In order for the number’s ones digit to be 0, must remove 28 (ones digit is 8 ) so that we can get 0 as the ones digit of the number

Sum = 29 + 32 + 45 + 29 + 47 + 17 + 11 = 210

[cafelatte]

Brilliant ! Thanks Dharma ! Why didn't I think of that ?

[P5G]

cafelatte:

Need to know the step-by-step thinking procedure for solution this question :


When one of the following numbers is excluded, the sum of the remaining numbers is divisible by 2,3 and 5. What is the number?
29,28,32,45,29,47,17,11?

29 + 28 + 32 + 45 + 29 + 47 + 17 + 11 = 238

2 x 3 x 5 = 30

238/30 = 7 r 28 --> remove 28

[BigDevil]

stuckinratio:

Hi maths guru,


have this q

The no of cakes was twice the no of cream puffs. After 90 cakes and 42 cream puffs were sold, the ratio of the no of cakes left to the no of cream puffs was 2:5. How many cakes and cream puffs were in the shop at first?

TIA

(oops- new to this and posted a new thread instead -sorrieee)

Is there something wrong to this question?
I tried using modeling, then I tried solving with algebra.
Both times I can't get a nice round answer.
Cake = 91.5; cream puff = 45.75

However, if I reverse the condition to no. of cream puffs was twice the no. of cakes, then final answer is cake 366, cream puffs 732.

[tianzhu]

BigDevil:

Is there something wrong to this question?
I tried using modeling, then I tried solving with algebra.
Both times I can't get a nice round answer.
Cake = 91.5; cream puff = 45.75

Hi BigDevil

The original question is likely to be flawed.

You are now emerging into a confident new breed problem solver ready to run the next lap.

We look forward to more of your solutions.

Best wishes

[BigDevil]

tianzhu:

Hi BigDevil


The original question is likely to be flawed.

You are now emerging into a confident new breed problem solver ready to run the next lap.

We look forward to more of your solutions.

Best wishes

:oops: :oops: still learning the ropes only...
班门弄斧 贻笑大方 :oops: :oops:

[tianzhu]

BigDevil:

:oops: :oops: still learning the ropes only...
班门弄斧 贻笑大方 :oops: :oops:

Hi BigDevil

If you feel that I am making fun of you, I sincerely apologise.

I am no expert, just a dad who is thick skinned enough to put my solutions online. For a forum to be vibrant, we need more new problem solvers who are ready to inject new ideas. The intention of my earlier post is to encourage more active participation from new problem solvers.

Best wishes

[Muffins]

Hi guys, when I did the cream puff cake question, I got 66.5 cakes, 33.25 cream puffs. Could you explain, BigDevil or Tianzhu? Thanks…