A staight pipe of 20m is their.A man climb it 5m in a day and slips 2.5m in night. so how much days it will take to climb
end of day 1 -- 5 m
end of night 1 -- 2.5
end of day 2 --- 7.5
end of night 2 -- 5
end of day 3 -- 10
....
so the increase each day and night = 2.5 m
we have an AS where
a = 5
d = 2.5
term(n) = 20
term(n) = a + (n-1)d
20 = 5 + (n-1)(2.5
20 = 5 + 2.5n - 2.5
17.5 = 2.5n
n = 7
he will reach the top at the end of day 7