A man was trying to swim a buoy placed at a distance of 200m out in the sea. It took him 1min to swim 20m. Then a wave pushed him back 10m and he rested for about 1min before swimming again. He continued i this way for the rest of the journey. How long would it take the man to swim to the bouy? help me with this please^-^

Question

A man was trying to swim a buoy placed at a distance of 200m out in the sea. It took him 1min to swim 20m. Then a wave pushed him back 10m and he rested for about 1min before swimming again. He continued i  this way for the rest of the journey. How long would it take the man to swim to the bouy? >help me with this please^-^

unklerhaukus · Answer

so after 1 minute the swimmer is 20m out to sea, after 2mins at 10m out. 

after 3 mins   30m,       4 mins 20m,

. . . .

anonymous · Answer

But I need to show the working, is there any type of formula I could use?

unklerhaukus · Answer

It looks like some kind of series

anonymous · Answer

hmm

anonymous · Answer

its sort of a sequence..

unklerhaukus · Answer

a sum of arithmetic sequences?

anonymous · Answer

yes it is.

unklerhaukus · Answer

so what is the common difference for each of the sequences

anonymous · Answer

idk actually, The formula is: 20+(n-1)*10=200
I wanna know if theres another easier method to do it:/