Question
Water lillies double in area every 24 hour. In spring there is one water lily on a lake. In sixty days, the lake is completely covered with lillies. how many days did it take to cover half the lake
Answers
Damon
1 2 4 8 16
1 2^1 2^2 2^3 2^(n-1)
a a2^1 a 2^2 ....
geometric sequence with
a = 1
r = 2
n = number of days
2^59 = area
2^x = 2^59/2
x = n-1 = 58 so 59 days
which we could have said right off
because if you cover the whole lake in 60 days then the day before you must have half the lake covered.
1 2^1 2^2 2^3 2^(n-1)
a a2^1 a 2^2 ....
geometric sequence with
a = 1
r = 2
n = number of days
2^59 = area
2^x = 2^59/2
x = n-1 = 58 so 59 days
which we could have said right off
because if you cover the whole lake in 60 days then the day before you must have half the lake covered.
Vsvgshs
Answer 58
Ajjubhai 94
Anish is right