Melody

ok Now i get it!

He left out the y

How many inches. 

He actually needs to make $11.67 PROFIT on each bag.  

So he will need to sell them for the Cost Price + $11.67

Hi Sir Alan,

Please do not be offended but I am amused by what you think is good idea.   

BUT I will still try and work out what you are telling me.    

the first line is good   I am glad i can understand that much.

But, where did the 2n+1 that you have everywhere come from?  

Hi Dragon,

$$As a fraction 22 out of 120 is $\frac{22}{120}$\\
and if you want to change a fraction to a percentage then you have to multiply by 100.\\
$\frac{22}{120}\times 100=18.33333333...\%$\\
Rounded to 1 decimal place this is 18.3\%$$

Does that make more sense now Dragon?

Oh sorry, I thought you needed more explanation - I didn't read what you said properly. 

Just use the compound interest formula

$$$FV=P(1+i)^n$\\
where n=15\\
i=1.06/100=0.0106\\
P=25000$$

You can take over from here.  

Takahiro I think you may have forgotten one minus sign.  Two of your answers are the same. (The last 2)

Also your answers are approximations.  You would be better off to stick to exact answers.  

I gave you thumbs up though.  Thanks

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NOW I am looking at these answers and I can certainly see that they work BUT to find these for this or a similar question what do I need to know or keep in mind?

$$[\pm(1\pm i)]^2=\pm2i\;\rightarrow \;[\pm2i]^2=-4$$

Do I need to commit this to memory?

I suggest you google it.  You would have had your answer long ago. 

Why don't you provide us with an example and then we will show you. 

Excellent point Chris. 

I am impressed but what do you mean by "you did it without colour"?