Answer:
36
Step-by-step explanation:
3(15.9 - 3.9)
3 · (15.9 - 3.9)
3(15.9) - 3(3.9)
47.7 - 3(3.9)
47.7 - 11.7
36
Answer:

Step-by-step explanation:
The sum of an infinite geometric series is expressed according to the formula;
where;
a is the first term of the series
r is the common ratio
If the sum of an infinite geometric series is three times the first term, this is expressed as 
Substitute
into the formula above to get the common ratio r;


open the parenthesis

subtract 3 from both sides

<em>Hence the common ratio of this series is </em>
<em></em>
Answer:
6 knots
Step-by-step explanation:
Let the speed be v knots
then time taken to cover 500 M = 500 / v hrs
fuel consumption /hr = 216 + 0.5v^3
let F be the fuel consumption for trip
= [500/v][216 + 0.5v^3]
= 500[216/v + 0.5v^2]
dF/dv = 500[ - 216/v^2 + v]
d^2F/d^2v = 500[432/v^3 + 1] , i.e. +ve
so setting dF/dv will give a minima
500[ -216/v^2 + v] = 0
or v = 216/v^2
or v^3 = 216
solving, we get v = [216]^(1/3) = 6 knots
A = 1/2 b h
5 = 1/2 (5) h
10 = 5h
h = 10/5
h = 2
answer
2
The 3rd one is the right one!!!!!!!!!!!!!!!!!!