Foundation November 2019 Paper 3 Q14
14 Here is a rectangle.
Coby has to find the perimeter of this rectangle.
He writes,
Perimeter \(= 7 \times 3\)
(a) What mistake has Coby made? (1)
Here is a triangle.
Iram solves a problem about this triangle to find the value of \(x\).
Her answer is
\(x = -2\)
(b) Explain why Iram’s answer must be wrong. (1)
| Answer | Mark | Mark scheme |
|---|---|---|
| Explanation | C1 | for a correct explanation, eg that he has found the area not perimeter Acceptable examples He has found the area (not perimeter) He should have added The perimeter is \(7+3+7+3\ (=20)\) oe He did base\(\times\)height He has timesed (not added) Not acceptable examples He has worked it out wrong He should have squared it He should have done \(14 \times 6\) or \(7 \times 3 \times 7 \times 3\) or \(7 \times 3\) twice then add them He didn’t include the top or the other side He should have doubled it It should be \(P = 7 \times 3\) or he has done the sum not found the answer |
Additional guidance
Any incorrect statement as part of a correct response can be ignored unless it contradicts the statement, eg, he found area but perimeter equals 10
| Answer | Mark | Mark scheme |
|---|---|---|
| Explanation | C1 | for correct explanation, eg that you cannot have a length of \(-2\) Acceptable examples \(x\) cannot be negative Cannot have a negative length Has to be positive It is impossible Can’t have \(-2\)(cm) (as a measurement) It has to be more than 0 Not acceptable examples You can have \(-2\) Won’t add to 180 He has a minus sign and the other sides have add signs It has to be a whole number or decimal there are no negative numbers to get a negative answer there is no cm after his answer It should be +2 |
Additional guidance
Any incorrect statement as part of a correct response can be ignored unless it contradicts the statement.