problem 179 penguin problem

Mathematics
Tutor: None Selected Time limit: 1 Day

There are 190 penguins standing near the beach, and then one penguin dives into the sea, followed by two penguins, then three penguins, and so on, with one more penguin in each group. How many penguins will be in the last group?

Aug 21st, 2014

19 penguins in the last group

(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19) =19

sum to n terms  is (1+2+...+n) = n(n+1)/2 =190

n(n+1) =2*190

n(n+1)-380=0

n^2+n-380=0

n^2+20n-19n-380=0

n(n+20)-19(n+20)=0

(n+20)(n-19)=0

n=19

Last group contains 19 penguins

Aug 21st, 2014

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.
Click to visit
The Notebank
...
Aug 21st, 2014
...
Aug 21st, 2014
Dec 4th, 2016
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer