Maths problem.. please help

daveyjp

There are two 'D's in the first equation, but one is 'hidden' by the brackets.

First job to get the equation in terms of A is to lose the brackets.

If you expand the brackets you get 2Ds in the equation:

(A+1)D = (AD)+(1D)

(1D)=D

so

(A+1)D = AD+D

dmg24

My lecturer would have a fit if I had the same term on the top and the bottom!

c = ((A+1)D)/24
24c/D = A + 1
((24c)/D) - 1 = A

Also, A = the age of the child. The question doesn't actually ask for that?!

First thing I tell my students - make sure you answer the question! x

daveyjp

My version is probably not mathmatically correct, but the answer is the same whichever version you use.

As you said:

"Also, is A the age of the child? If so, then the second part of the question cannot be answered"

It can be answered if you find A first which as we have shown can be done. This isn't the answer to the question, but it's on the route to the solution.

I'd be interested to know if the two questions had different marks allocated to them. i.e. Question 1 was worth 5 marks, question 2 10 marks. If so it would indicate to me question 2 was harder than question 1 and required a bit more than simply slotting numbers into an equation already given.

devilgirls1

i had 30 questions and each was worth 1 point.. got a retake next week and considering i got 18/30 i just need to get a couple more right as the tutor says the test is very similar to the 1st one..

thanks everyone for all your help.

Mics_chick

dmg24 wrote: »

Found it - Cowling's Rule:



c = ((child's age + 1)/24) x (adult dose)

c = 4/24 x 36 = 6 mg

10 = ((child's age + 1)/24) x (adult dose)
240/(child's age + 1) = adult dose*

* cannot give final answer without knowing age of child

This is the right answer :T :T :T

I got an 'A' grade O-level Maths 20+ years ago and have forgotten alot of it :rolleyes: but looking through this thread has reminded me of it :j

Sometimes equations don't come to a definite numerical answer - that's why they're an equation... and stay an equation

So the 2nd part is asking what the equation would look like if you needed to find the adult dose...

devilgirls1

is it ok to ask advise on the other questions i had, just want to see how i went wrong?

will post later on today/tommorow

ffeindadifyr

Go ahead.... I don't mind having a look at them

devilgirls1

these are the ones i remember, no calculators allowed in test..

1) whats 3.477 rounded up to 2 decimal points?

2) if 100g flour makes 15 biscuits how much would..
a- 1000g flour make
b-how much flour would be needed for 9 biscuits

3) Y=6X-7

make X the subject

4) x2+3=25

(the x2 is actually small and x and a small 2 which is above the x)


5) junction 10 to 16 on the m25 is 10 miles

a- if it took 12 mins from juction 10 to 16 what speed would you be going at?
b- if you were going 60mph how long would it take?

6) a brass nail is 8:1 for copper and tin

a-if the total weigh of the nail is 18g what was the weight of the copper in the nail?
b- if the tin in the nail is 1.5g what is the total weigh of the nail?

7) whats the volume of a cube 5cm?

8a) a triangle has sides ABC, one is 4cm and the other 3cm, find the third side?

b- whats the total area for the triangle? (no pic of the triangle)

9) a circle has a radius of 2cm, whats the total area for the circle?

10a) whats the square root of 27

b- 26 (its a tiny six next to the 2)

11) if 15 million people are available to work in the uk whats..

a- if 3 million are ready for work whats the percentage?
b-if 5% are unemployed, whats the total no. unemployed

12)radon gas turns to liquid at -82 degrees
butane gas turns to liquid at -182 degrees

a- at what point was radon still a gas?
b- give a the temp of when radon is still a gas but butane a liquid?

Broke_Student

Not done much maths in two years but ill give it a shot! These will probably need checking...

devilgirls1 wrote: »

these are the ones i remember, no calculators allowed in test..

1) whats 3.477 rounded up to 2 decimal points?
3.48

2) if 100g flour makes 15 biscuits how much would..
a- 1000g flour make
150
b-how much flour would be needed for 9 biscuits
60g

3) Y=6X-7
make X the subject
x=(y+7)/6

4) x2+3=25
(the x2 is actually small and x and a small 2 which is above the x)
duuno :eek:


5) junction 10 to 16 on the m25 is 10 miles

a- if it took 12 mins from juction 10 to 16 what speed would you be going at?
50mph
b- if you were going 60mph how long would it take?
10mins

6) a brass nail is 8:1 for copper and tin

a-if the total weigh of the nail is 18g what was the weight of the copper in the nail?
14.8g?

b- if the tin in the nail is 1.5g what is the total weigh of the nail?
8.46g?

7) whats the volume of a cube 5cm?
125cm^3

8a) a triangle has sides ABC, one is 4cm and the other 3cm, find the third side?
don't we need to know which side it is?

b- whats the total area for the triangle? (no pic of the triangle)

9) a circle has a radius of 2cm, whats the total area for the circle?
12.57cm^2

10a) whats the square root of 27
5.196

b- 26 (its a tiny six next to the 2)
5.01

11) if 15 million people are available to work in the uk whats..

a- if 3 million are ready for work whats the percentage?
20%
b-if 5% are unemployed, whats the total no. unemployed
750000

12)radon gas turns to liquid at -82 degrees
butane gas turns to liquid at -182 degrees

a- at what point was radon still a gas?
the point before before it was a liquid
b- give a the temp of when radon is still a gas but butane a liquid?
i work out that the ranges don't overlap

suffolkb

Qu.8. It`s a 3,4,5 triangle (Pythag), giving area as half base * height = 1/2 *3*4 = 6.
Haven`t checked the rest - got to go out.