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The Bambanani Crèche in Bethlehem bought the cubic blocks below from an auction - NSC Mathematical Literacy - Question 3 - 2019 - Paper 1

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The Bambanani Crèche in Bethlehem bought the cubic blocks below from an auction. They have a side length of 45 cm. On two opposite sides of the block is a circular h... show full transcript

Worked Solution & Example Answer:The Bambanani Crèche in Bethlehem bought the cubic blocks below from an auction - NSC Mathematical Literacy - Question 3 - 2019 - Paper 1

Step 1

3.1.1 (a) Calculate the area (in cm²) of ONE of the faces of the block that does not have a circular hole.

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Answer

To calculate the area of one face of the cube, we can apply the formula:

Area=sideimesside=45extcmimes45extcm=2025extcm2Area = side imes side = 45 ext{ cm} imes 45 ext{ cm} = 2025 ext{ cm}²

Thus, the area of one face without a circular hole is 2025 cm².

Step 2

3.1.1 (b) Show that the total surface area of the faces with circular holes = 11 582,869 cm².

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Answer

First, calculate the area of the circular holes using the formula:

Areacircle=extπimesr2=3,142imes(9,5extcm)2=283,655extcm2Area_{circle} = ext{π} imes r^2 = 3,142 imes (9,5 ext{ cm})^2 = 283,655 ext{ cm}²

The area for one face with a hole includes the area of the face without the hole minus the area of the hole:

Areafaceextwithhole=AreafaceAreahole=2025extcm2283,655extcm2=1741,345extcm2Area_{face ext{ with hole}} = Area_{face} - Area_{hole} = 2025 ext{ cm}² - 283,655 ext{ cm}² = 1741,345 ext{ cm}²

For the two faces with holes, multiply by 2:

TotalextSurfaceArea=2imes1741,345extcm2=3482,69extcm2Total ext{ Surface Area} = 2 imes 1741,345 ext{ cm}² = 3482,69 ext{ cm}²

Adding the area of the remaining faces:

Total=3482,69+(42)imes2025=11582,869extcm2Total = 3482,69 + (4 - 2) imes 2025 = 11582,869 ext{ cm}²

Hence, the total surface area of the blocks with circular holes is 11 582,869 cm².

Step 3

3.1.1 (c) Calculate the total amount of paint needed to paint 12 chairs with ONE coat of paint.

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Answer

First, calculate the total surface area for all chairs:

TotalextSurfaceAreafor12chairs=12imes11582,869extcm2=139994,428extcm2Total ext{ Surface Area for 12 chairs} = 12 imes 11 582,869 ext{ cm}² = 139 994,428 ext{ cm}²

Next, find how much paint is needed:

Amount ext{ of paint} = rac{139 994,428 ext{ cm}²}{15 ext{ cm}²} imes 1,8 ext{ m²} = 1 389 944,28 ext{ cm²}

To convert cm² to litres, remember that 1 ℓ = 1000 cm³. Rounding off yields approximately 17 ℓ of paint required.

Step 4

3.1.2 (a) Write down the diameter of the tin.

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Answer

The diameter of the tin can be calculated using the radius:

Diameter=2imesr=2imes7extcm=14extcm.Diameter = 2 imes r = 2 imes 7 ext{ cm} = 14 ext{ cm}.

Thus, the diameter of the tin is 14 cm.

Step 5

3.1.2 (b) Calculate the height of the paint in the tin.

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Answer

Using the volume formula:

Volume = ext{π} imes (r)^2 imes height ightarrow height = rac{Volume}{ ext{π} imes (r)^2}

Substituting in:

height = rac{5000 ext{ cm}³}{3,142 imes (7 ext{ cm})^2} = rac{5000}{3,142 imes 49} ightarrow height = rac{5000}{153,938} ightarrow height ext{ is approximately } 32,48 ext{ cm.}

Hence, the height of the paint in the tin is approximately 32,48 cm.

Step 6

3.2.1 Determine if a 37-year-old man with a WHR of 0,95 has a moderate or a high risk of obesity.

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Answer

According to the provided classification:

  • A WHR of 0,95 falls into the category of moderate risk for men aged 20-39 years (as it is between 0,84 and 0,96).

Thus, the man has a moderate risk of obesity.

Step 7

3.2.2 Calculate this man's WHR.

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Answer

Using the formula for WHR:

WHR = rac{waist ext{ measurement}}{hip ext{ measurement}} = rac{105 ext{ cm}}{92 ext{ cm}} = 1,141.

Hence, the man's WHR is 1,141.

Step 8

3.2.3 (a) State ONE possible age group of this woman.

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Answer

The age group could be 40 to 49 years old or 50 to 59 years old, as she fits the profile of a moderate risk with a WHR of 0,7826.

Step 9

3.2.3 (b) Calculate the woman's hip measurement.

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Answer

Using the WHR formula:

0,7826 = rac{72 ext{ cm}}{hip ext{ measurement}}

Rearranging gives:

hip ext{ measurement} = rac{72}{0,7826} ightarrow hip ext{ measurement} ext{ is approximately } 91,57 ext{ cm.}

Rounding off yields a hip measurement of 92 cm.

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