Answer: c) 15
Step-by-step explanation:
3, 8, 13, 18, ... - the arithematic progression an=73 n=?
Difference of an arithmetic progression: d=a₂-a₁.
a₁=3 a₂=8
Hence,
d=8-3
d=5
Nth element of an arithmetic progression
[tex]\boxed {a_n=a_1+(n-1)*d}[/tex]
[tex]73=3+(n-1)*5\\73=3+5n-5\\73=5n-2\\73+2-2=5n-2\\75=5n\\[/tex]
Divide both sides of the equation by 5:
[tex]15=n[/tex]
