I have concerns regarding questions attached.

2.13- Can someone verify my results, am I doing this question correctly? (See 2nd attachment)

2.17- I'm not sure how to do this one, I think I understand what I need to do in my head I'm just having trouble working out the math.

Firstly, what do they mean byeffectiveinterest rate? Is it still compounded monthly?

Here is my attempt at the single payment option:

Is this correct?

I'm not sure how to deal with the 12 payments as opposed to one single payment at the end. If we assumed one single payment at the end it would be as follows,

How do I deal with 12 equal payments effectively decreasing the balance on which compounding interest is collected each month?

Thanks again!