Answer:
690
Step-by-step explanation:
The multiples of 3 between 5 and 64 are 6+9+12+15+18+21+24+27+30+33+36+39+42+45+48+51+54+57+60+63 which gives you 690.
Hope this helps, have a good day! :D
Answer: ∑=690
Step-by-step explanation:
Let's use the formulas for an arithmetic progression:
[tex]a_1=6 \ \ \ \ \ a_n=63\ \ \ \ d=3\\a_n=a_1+(n-1)d\\63=6+(n-1)3\\63=6+3n-3\\63=3+3n\\63-3=3+3n-3\\60=3n\\[/tex]
Divide both parts of the equation by 3:
[tex]20=n[/tex]
Thus,
[tex]\displaystyle\\\sum=\frac{a_1+a_n}{2} n\\\\\sum=\frac{6+63}{2}20 \\\\\sum=\frac{69*20}{2} \\\\\sum=69*10\\\\\sum=690[/tex]
