Correct answer only scores full marks (unless from obviously incorrect working) Answer: \(1684\pi\)
A1
(5)
(5 marks)
Notes
M1: oe for forming a correct equation; allow use of any letter
M1: for a correct method to find the radius of the hemisphere
M1ft: for a method to find the area of the top of the bowl or the total area of the two curved surfaces of the bowl
where [21] is what they believe to be radius of the hemisphere
M1ft: ft their [21] for a complete method
A1: cao
SCB4 for \(2028\pi\) (use of 23 as the outer radius)
M2 for use of formula for total surface area of hemispherical shell in a complete method, eg \(3\pi([21])^2 + \pi([21] - 2)^2\) oe If not M2, allow M1 for this formula used with omission of \(\pi\) eg \(3([21])^2 + ([21] - 2)^2\)
(measurements with intention to add for the 2nd M mark)
Surface area = “120” + “90” + “150” + “24” + “24”
[allow “120” + “90” + “150” + “48” + “48”]
M1
Correct answer scores full marks (unless from obvious incorrect working) Answer: 408
A1
(3)
(3 marks)
Notes
M1: For a correct method to find the areas of 2 different faces (ie not 2 triangles) allow 8 × 6 as one area
(allow with incorrect areas for this mark)
M1: for adding together 4 or 5 values for area (condone 48 as 1 or 2 areas) at least 3 of which are from a correct method
NB: (6 + 8 + 10) × 15 (sum must be seen) is 3 faces but only award this if clearly not intended to be the volume – eg by the addition of the area of a triangular end.
A1: cao SCB2 for an answer of 456 if no other marks awarded
