Question 560284
The formula to calculate surface area of a cylinder is {{{S=2pi*rh+2pi*r^2}}} (You had a typo).
The formula to calculate its volume is {{{V=pi*r^2h}}}
Using the measurements in cm, square centimeters (sq cm), and cubic centimeters (cc) would be best.
1 mm = 0.1 cm, so 8 mm = 0.8 cm and 1.5 mm = 0.15 cm (you just divide by 10)
1 m = 100 cm, so 8 m = 800 cm and 1.5 m = 150 cm (you just multiply times 100)
Your teacher probably expects you to use the approximation {{{pi}}}=3.14, so I'll use that.
a)  For a cylindrical ant that is 8 mm long and has a radius of 1.5 mm:
S = {{{2pi*0.15*0.8+2pi*0.15^2}}} = approx. 0.89 sq cm
V = {{{pi*0.15^2*0.8}}}{{{cm^3}}} = approx. 0.057 cc
In one second, it would absorb {{{6.2*0.89*1}}} mL oxygen = 5.5 mL oxygen.
During that second it would require {{{24*0.057*1}}} mL oxygen = 1.37 mL oxygen.
This ant would have a surface area large enough to meet its oxygen needs.
b) For a "giant" ant that is 8m long and has a radius of 1.5m (1,000 times longer in every direction):
S = {{{2pi*150*800+2pi*150^2}}} = 890,000 sq cm = {{{8.9*10^5}}} sq cm
V = {{{pi*150^2*800}}}{{{cm^3}}} = approx. 57,000,000 cc = {{{5.7*10^7}}} cc
In one second, it would absorb {{{6.2*8.9*10^5*1}}} mL oxygen = 5,500,000 mL oxygen = {{{5.5*10^6}}} mL oxygen.
During that second it would require {{{24*5.7*10^7*1}}} mL oxygen = 1,370,000,000 mL oxygen = {{{1.37*10^9}}} mL oxygen.
This ant would not have a surface area large enough to meet its oxygen needs.
c) Substituting 1000r for r and 1000h for h into the formulas for surface area and volume, we see that
S = {{{2pi*(1000r)(1000h)+2pi*(1000r)^2}}} = {{{1,000,000(2pi*rh+2pi*r^2)}}} and
V = {{{pi*(1000r)^2(1000h)}}} = {{{1,000,000,000(pi*r^2h)}}} 
With the same shape, as the length measurements increase by a factor of 1,000, the surface are increases by a factor of 1,000,000 (1,000^2), and the volume increases by a factor of 1,000,000,000 (1,000^3).
NOTE: The same is true for any shape (not just cylinders), and any factor (not just 1,000).