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The curved surface area of a right circular cylinder is 616 cm2 and the area of its base is 38.5 cm2. What is the volume (in cm3) of the cylinder? (Use π=722)
1078
1155
1243
1408
1078
Notice that Volume = (Base Area) * (Height). Since CSA = 2 * (Base Area) * (h/r), you can find the height h by relating the two given area equations.
Curved surface area (CSA) = 616 cm², Base area = 38.5 cm², π=22/7
CSA=2πrh, Base Area=πr2, Volume=πr2h
Notice that Volume = (Base Area) * (Height). Since CSA = 2 * (Base Area) * (h/r), you can find the height h by relating the two given area equations.
Students often try to solve for height without finding the radius first, or confuse diameter with radius.
Calculate the radius
Given the base area is 38.5 cm², we solve for the radius r using the formula for the area of a circle: πr2=38.5. Substituting π=22/7, we get 722r2=38.5, so r2=2238.5×7=12.25. Thus, r=12.25=3.5 cm.
r=3.5 cm
Calculate the height
Given the curved surface area (CSA) is 616 cm², we use the formula 2πrh=616. Substituting the known values: 2×722×3.5×h=616. Simplifying: 2×22×0.5×h=616, which gives 22×h=616. Therefore, h=22616=28 cm.
h=28 cm
Calculate the volume
Finally, calculate the volume using the formula V=Base Area×h. We have V=38.5×28=1078 cm³.
V=1078 cm3
A is correct because the calculation of the radius (3.5 cm) and height (28 cm) leads to a total volume of 1078 cm³.
Always verify if the question gives the area of one base or total surface area; here it explicitly states base area.