Answer:
a₃ = 1.25
Step-by-step explanation:
the sum to infinity is calculated as
S ∞ = [tex]\frac{a_{1} }{1-r}[/tex]
a₁ is the first term and r the common ratio
given a₁ = 5 and S∞ = 10 , then
10 = [tex]\frac{5}{1-r}[/tex] ( multiply both sides by (1 - r)
10(1 - r) = 5
10 - 10r = 5 ( subtract 10 from both sides )
- 10r = - 5 ( divide both sides by - 10 )
r = 0.5
then
a₂ = a₁ × r = 5 × 0.5 = 2.5
a₃ = a₂ × r = 2.5 × 0.5 = 1.25
