1.$47 tie; 4.5% markup 2. $49.95 CD player; 5% tax

3. $22 haircut; 20% tip

4. $8.75 breakfast; 15% tip

5. $40.80 dinner; 17% tip

6. $18.99 CD; 6% markup

Work Shown:

a = 3 is the first term

r = 2 is the common ratio

Sn = a*(1-r^n)/(1-r) ... sum of the first n terms

S8 = 3*(1-2^8)/(1-2) ... sum of the first 8 terms

S8 = 3*(-255)/(-1)

S8 = 765

We can generate the first 8 terms to get 3, 6, 12, 24, 48, 96, 192, 384. Each new term is found by multiplying the previous one by 2.

Then add them up to get 3+6+12+24+48+96+192+384 = 765. We get the same result.