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Surface Area and Volume of 3D Solids Summary — Free MYP5 Mathematics (Standard) Practice Questions
1QuestionReal-Life Applications of Volume and Surface AreaConcept Practice
2 marks~3 minCriterion C
A cylindrical water tank has radius r=3 m and height h=5 m. A maintenance company charges 12 dollars per m2 to apply a protective coating to the curved surface only.
a
State the formula for the curved surface area of a cylinder and calculate the curved surface area of this tank. [1]
b
The maintenance company quotes a total cost of 1131 dollars. Justify whether this quote is consistent with the given charge rate. [1]
Solutions
2QuestionSurface Area of Cylinders and PrismsAssessment Practice
5 marks~8 minCriterion D
A manufacturer drills a cylindrical hole of radius 2 cm through the centre of a solid rectangular block measuring 8 cm × 6 cm × 5 cm. The hole runs parallel to the 8 cm edge, passing completely through the block. Every exposed surface of the finished block must be coated with a protective compound.
Use π=3.14.
a
Calculate the total surface area of the original rectangular block. [1]
b
Calculate the total surface area of the finished block after the cylindrical hole has been drilled. [2]
c
The coating costs 0.08 dollars per cm². Advise the manufacturer whether a single 25-dollar tin of coating is sufficient, justifying your answer with reference to the calculated cost and any practical risk. [2]
Solutions
3QuestionSurface Area of Cylinders and PrismsConcept Practice
6 marks~9 minCriterion A
A manufacturer produces open-topped gift boxes by cutting and folding cardboard. Each box is a rectangular prism with a fixed base of 4cm by 6cm and a variable height of hcm, where h is a positive integer. The total surface area S (in cm2) of the closed box is given by
S=2(4×6)+2(4h)+2(6h)=48+20h.
a
Calculate S for h=1,2,3,4,5,6 and record your results as a sequence. [2]
b
Deduce the surface area when h=10 by identifying the pattern in your sequence. Do not use the formula directly. [2]
c
The manufacturer requires a total surface area of at most 300cm2 to keep material costs viable. Advise the manufacturer whether h=13 is a suitable production height, justifying your answer with a calculation and a reference to the constraint. [2]
Solutions
4QuestionNets and Surface Area of Cubes and CuboidsAssessment Practice
6 marks~9 minCriterion B
A packaging company designs closed rectangular boxes with a fixed volume of 24 cm3. Minimising surface area reduces material cost.
a
Calculate the surface area of each box using S=2(lw+lh+wh). [2]
Dimensions (l,w,h) in cm: (1,4,6); (2,3,4); (1,3,8); (2,2,6).
b
Justify which set of dimensions minimises surface area by identifying a geometric property shared by those dimensions. [1]
c
Let the dimensions be x, y, z with xyz=24. Show that S=2(xy+x24+y24). Hence prove, using the AM–GM inequality, that surface area is minimised when all three dimensions are equal. Advise the company whether to use the (2,3,4) box or commission a new cubic design, justifying your recommendation with reference to the theoretical minimum. [3]