Maths questions

Srengam · 7 Sep 2011 at 21:01

+1 for what Davefram said about workings (sorry Energizer Bunny). Just two of my assignments for this year have been answer only, the other 5 have been with full workings.

(currently doing Maths degree).

It may also depend on the University too I suppose.

Judgeneo · 8 Sep 2011 at 09:32

Srengam said:
+1 for what Davefram said about workings (sorry Energizer Bunny). Just two of my assignments for this year have been answer only, the other 5 have been with full workings.

(currently doing Maths degree).

It may also depend on the University too I suppose.

Its the same for my degree as well (maths and physics) but no-one expects you to put the working out for basic multiplication and division

Back when your learning it yes, but not now

Davefran · 8 Sep 2011 at 17:14

Srengam said:
Different types of calculators will give different answers for arithmetic.

Eg,

2x2+2x2+2x2+2x2 will give 92 on a normal cheap calculator, a scientific or graphics calculator will give 16 (which is correct).

Wrong the correct answer is 60

(2x2)+(2x2)+(2x2)+(2x2) would be 16 lol

Srengam · 8 Sep 2011 at 20:30

? How are you getting 60?

2x2+2x2+2x2+2x2=16, the brackets don't need to be present.

DAnDan · 8 Sep 2011 at 20:32

Srengam said:
? How are you getting 60?

2x2+2x2+2x2+2x2=16, the brackets don't need to be present.

Correct.

cainer · 8 Sep 2011 at 20:35

Srengam said:
? How are you getting 60?

2x2+2x2+2x2+2x2=16, the brackets don't need to be present.

2x2 is 4, +2 = 6, x2 = 12,+2 = 14, x2 = 28, +2= 30, x2 = 60

Srengam · 8 Sep 2011 at 20:38

Ahh, I see what you mean, on a cheap calculator it is 60. Ie, I actually got the wrong answer wrong LOL.

dowie · 8 Sep 2011 at 21:27

nayan89 said:
yeah it's 80%

all you do is 4/5 of 420, which gives you 336.

336/420 = 0.8 (80%)

erm that's a bit silly

Davefran · 8 Sep 2011 at 23:49

Srengam said:
Ahh, I see what you mean, on a cheap calculator it is 60. Ie, I actually got the wrong answer wrong LOL.

I did it in my head, the correct way, as shown by cainer

nightrider1470 · 13 Sep 2011 at 12:38

Am a bit puzzled here, but am sure its quite obvious if someone could explain

One of my questions is basically showing a small box with measurements around it and a much larger box and asking how many smaller boxes can fit inside

I got the question wrong but am still confused even knowing what the right answer is!! I understand that I need to devide each L W H by each box but confused how 0.5m devided by 12cm = 4 ???

box 1
Lengh > 12cm
width > 20cm
Height > 5cm

Box 2
Lengh > 0.5m
Width > 0.4m
Height > 0.2m

answers = 4 , 2 , 4 then I need to 4 x 2 x 4 = 32

I just need help to understand how say 0.5m devided by 12cm = 4 or 0.4m devided by 20 = 2 ? how is that caculation done so I can work it out ?

Six7th · 13 Sep 2011 at 12:44

0.4m is 40cm, so 40/20=2
0.5m is 50cm, so 50/12=4.1667

It's much easier if you find the volume of each box, then divide the volume of box 2 by box 1.

Judgeneo · 13 Sep 2011 at 12:50

Six7th said:
It's much easier if you find the volume of each box, then divide the volume of box 2 by box 1.

That only works if the boxes are an exact fit. In this case, dividing the volumes would give you an answer of 33(.333333) When the answer is actually 32

nightrider1470 · 13 Sep 2011 at 12:51

Thanks so much

Can you advise a easy method to find out percentages of things ?

ie whats 28% of say 15400 people who smoke ?

Judgeneo · 13 Sep 2011 at 12:55

nightrider1470 said:
Thanks so much

Can you advise a easy method to find out percentages of things ?

ie whats 28% of say 15000 people who smoke ?

Percent. per-cent, cent standing for 100 as in century.

So 1 percent is 1 per 100, which can be expressed as 1/100 or 0.01 as well as 1% All are equivilent.

So 28% is the same as 0.28, so 28% of 15000 is 0.28*15000 which is 4200

DaveF · 13 Sep 2011 at 13:03

Judgeneo said:
Easiest way to divide 17.5 or similar by 5 is to recognise that 17.5 is 15 + 2.5 and divide both of them by 5 then add the results together. In this case, 15/5 is 3 and 2.5/5 is 0.5 so the answer is 3.5

Can't agree that's the easiest. Division by 5 is the same as doubling and then dividing by 10 (or vice versa if you prefer).

So 17.5 / 5 = (17.5 x 2) / 10 = 35 / 10 = 3.5

nightrider1470 · 13 Sep 2011 at 13:05

I understand

but my struggle would be pen to paper how to find out 28% divided by 15400 as am not to great at the technique used

I didnt attend school much when I was younger so things like this I wasnt taught, I work as a child care work so its not like I am thick but am trying to get to uni to do mental health nurse and have my maths exam I must pass today to get on the course. Had to learn all my maths I never learnt in school over the last 3 weeks!

Killerkebab · 13 Sep 2011 at 13:06

nightrider1470 said:
I understand but my struggle would be pen to paper how to find out 28 divided by 15400 as am not with working that out

Don't worry, I'm not sure how I'd lay out that long division either. All I could tell you is off the top of my head the result will be somewhere about 550 but I can't see for sure

Judgeneo · 13 Sep 2011 at 13:14

nightrider1470 said:
I understand but my struggle would be pen to paper how to find out 28% divided by 15400 as am not to great at the technique used

I didnt attend school much when I was younger so things like this I wasnt taught, I work as a child care work so its not like I am thick but am trying to get to uni to do mental health nurse and have my maths exam I must pass today to get on the course. Had to learn all my maths I never learnt in school over the last 3 weeks!

0.28*15000
= 28*150 (times one number by 100, divide the other by 100, net result the same)
= 20*150 + 8*150
= 3000 + 8*150
= 3000 + 4*300
= 3000 + 1200
= 4200

Does that help?

wilko49 · 13 Sep 2011 at 13:20

I don't think anyone's mentioned it in here, but the way to find the highest common factor (the largest number that two different numbers can be divided by) is to look for the prime factors - that is, numbers that are prime (you can't divide them and get a whole number) and are factors (you can divide the number by them).

For example, the prime factors of 6 are 2 and 3 (2x3 = 6), and the prime factors of 9 are 3 and 3 (3x3=9). So for that, the highest common factor is 3, because there is a 3 in each.

For your question, 28 = 2x2x7, so you can try dividing 15400 by each of those:

15400 / 2 = 7700
7700 / 7 = 1100
110 / 2 = 550 (550 isn't a prime factor, but you've used all of the factors from 28, so you can stop there.)

So 28/15400 = 2x2x7 / 2x2x7x550 = 1/550

Hope that helps, and good luck.

nightrider1470 · 13 Sep 2011 at 19:01

Thanks to you all

I passed