Melody

Is that your way of saying thanks to apsig.. ?

If AM = BM then these 2 arcs have the same length.

Yes that is obvious, but you have not said why  AM=BM    That is what I keep asking you.

Thanks for including the address of Chris's explanation. Now i understand.

The explanation is that since AB is a  diameter, the radius and the centre of the circle are easy to determine.

From that information, all else can be determined.

I read it as a total of 420 marbles put into box A and box B.

...  Some in box A and some in box B. 

That is why I could not do it.

Thanks aps.. 

 It does say a TOTAL of 420 marbles so it is badly worded.

It should have said 420 marbles are put into each of the two boxes.

I would like to see someone do this one too.    

The side lengths of a rectangle have been measured to the nearest half of a meter as 7.5 and 18.5.

What is the greatest possible percent error in finding the area of the rectangle?

the smallest possible sides could be  7 by 18  area = 126      difference from estimate = 12.75      12.75/126 = approx 10.1%

The estimate area = 7.5*18.5 = 138.75

the longest possible sides could be 8 bu 19    area = 152      difference from estimate = 13.25        13.25/152= approx 8.7%

I am no statistician, there is probably some more refined way to do this but I would assume the answer is 10.1% (to 1 dec place)

Thanks

But again I ask.

How did you determine this?

Continued here.

Yes I understand that, I was not accusing you of leaving anything out.

I just wonder if the original asker of the question left something out.

I assume you copied and pasted the question?

"A total of 420 green marbles and red marbles were put into Box A

and Box B respectively. There were 1 1/2 times as many red marbles as 

green marbles. Some yellow marbles were put into Box B. For every 

3 green marbles in Box A, 16 blue ones were added into Box A.

Box A then had four times as many marbles as Box B. What was the 

ratio of the number of yellow marbles to the number of blue marbles?"

I learnt Cramer's rule before I learn other methods but it is horrible.

I guess it is easy enough once you memorise all the steps but the steps make little sense to an ordinary person like me.

Matrices are brilliant for solving equations but Cramer's rule is far less intuitive than normal matrix elimination method.

Anyway.....

I suppose you have to learn Cramer's rule.

Here is a You Tube clip that is extremely well presented.

I am far from convinced that the question is answerable.