Okay, here we have this:
Considering the provided information< and measures, we are going to calculate the requested amount of rolls of paper, so we obtain the following:
So first we will calculate the area of each figure and finally we will add them to know the total area to cover. After that we divide that total area in the area that is covered by roll, then we have:
Cylinder surface area:
Cylinder surface area=2πrh + 2(πr2) = 2πr(h+r)
Cylinder surface area=2π(3 cm/2)(4 cm+3 cm/2)
Cylinder surface area=2π(1.5 cm)(5.5 cm)
Cylinder surface area=3π cm(5.5 cm)
Cylinder surface area=16.5π cm^2
Cylinder total surface areaA = 51.8364 cm^2
Hemisphere:
Total surface area of a hemisphere=(2πr^2) + (πr^2) = 3πr^2
Total surface area of a hemisphere=3π*(6.5 cm)^2
Total surface area of a hemisphere=3π*42.25 cm^2
Total surface area of a hemisphere=126.75π cm^2
total surface area= 398.1978 cm^2
Total area to cover = Surface area of the cylinder + Surface area of the hemisphere
Total area to cover = 51.8364 cm^2 + 398.1978 cm^2
Total area to cover = 450.0342 cm^2
Number of rolls=Total area / Area per roll
Number of rolls=450.0342 cm^2 / 25 cm^2
Number of rolls≈18
Finally we obtain that you need approximately 18 rolls of paper to wrap both presents.