2023 GSS 3E EOY Math Express Markers Report

Markers’ Report Subject : Mathematics Paper No : 1 Level/Stream : Secondary 3 Express Marker : Mark Lim & Chin Zhi Hao General Comments (for difficulty of paper, etc): The paper is generally difficult for the lower ability students. Graph reading and sketching prove challenging for the students. Qn Markers Feedback / Comments / Misconception / Errors Total possible mark for each question Put a  if the comment applies to some of the students in the class. Put  if the comment applies to > 50% of students All classes 3-7 3-8 3-9 +SBB 3-10 3-11 1 - Well done for this question - Students place 14%6 at the front 2   2 - Students uses compound interest to evaluate - Students who uses simple interest formula, stopped when they found $12574.20 2    3 - Done well for changing all numbers to 1 s.f. - Changing the final answer back of 0.25 to 0.3 - Students changing to 1 s.f. e.g. 4.45 to 4.00 3    4a Students conversion from only multiplying by the factor of  1  4b - Generally done well - Students conversion from only multiplying by the factor of 180 1    5 - Students can apply the formula for length segment but not able to manipulate to get the two required answers 3   6 - Generally done well - Students did not provide the correct rounding to 1 d.p. 2  

7 - Student did not apply the law of indices but instead multiply 1 749 to get the numerical number - Student attempted to guess the power of x from 0.05399 7 x 2   8 - Students stopped when they found the compound interest of $8499.3496 - Use of simple interest - Students are not able to correct the answers to nearest cents 3    9a - Mixed up with 1y x 1  9b - Generally done well 1  9c - Mixed up with 1y x 1  10 - Students used general formula to factorise 22 9 5 0xx   - Students did not reject the answer when x = −5 which would be good if indicated 3   11a - Generally done well - Students changed the inequalities sign when there was no multiplication / division of negative numbers 1   11b - Students indicated 1 as one of the prime numbers hence resulted in giving the wrong conclusion to the claims 2  12a - Students were not able to give the negative ratio for the cosine ratio 1  12b - Use of sine rule / cosine rule when a right-angle triangle is given 2   13a - Simplification of indices (e.g. 6 6 0a a a  ) resulted in lost of marks - Students did not simplify 0b 2   

13b - Generally done well - Marks were no wards if there are negative power (e.g. 5 55 or 0.2 aa   ) 2    14 - Not able to show the proper presentation in statement format - Incorrect or no reasons given (e.g. similar angle, similar side) - Students assumed that RC = 3 and used that in their proving for AC = AS which resulted in the use of wrong congruency tests - Student used Pythagoras’ theorem to find RS and equate to BC was incorrect also suggested the students’ assumption that AC was also 12 cm 3     15 - Not done well as students do not know how to start - Students had the misconception that 22(3 3 ) 3( )x y x y   - For students who started with 2(3 3 )xy , they wrote the expression as (3 3 )(3 3 )x y x y 2      16a - Handful of students committed an manipulation error e.g. 10 (0 5)(2(0) ) 5 b b     1  16b - Generally done well 1  16c - Students used complete the square method to get the max value of y. - Students were not able to correctly find the Line of symmetry. Error committed 5 ( 1) 32   2      17a - Well done 1  17b - Students did not attempt this part question - Students did not realise that the gradient of represent the speed of the object and continue to find the exact point at t = 40. 2   

- Students did not ignore the negative gradient  17c - Many students attempted to find the area under graph to find total distance travel and divide by the time taken - Students only used 50 km as the total distance instead of adding the return journey of another 50 km 2   18a Some students have the wrong shape of graph, doing exponential or cubic graphs. A few students plotted the graph, but failed to realise it’s a quadratic graph. 2  18b Some students draw a curve instead of a straight line. Many explained without drawing a line. 2  19a Many students can complete the square. Some students do – [6.52 + 9] to get –51.25 instead of the correct answer. 2     19b Many students ignore the “Hence” requirement of the question and use quadratic formula. 3  20a Many students do not know billion is 109. A few students write the working as 1.41 billion – 31.2 million. 2    20b Many students don’t understand the question, either dividing the wrong way, or using part (a) answer instead. 2      21a A number of students just give 265. 1  21b Most students can get the formula. 1  21c Most students are able to get 64 by solving or trial and error. 1  21d Some students left blank or did not explain much. 1  22 Most are able to draw a quadrilateral. Some did not draw bisectors accurately. Few are able to locate the region for P. Some just put a dot. 5  23a Most are able to show by substituting y = 8 or using gradient. 1  23b Very well done. Only a few substituted the wrong numbers. 2  23c Few students got it correct. Some students tried Add Math methods to get the answer. (Example: Using equation of perpendicular bisector) 3  24a Generally well done. 1 

24b Many are not able to visualise the required angle. Some did 122 – 92 instead of adding. 3  25a A number of students divided by 2 instead of 2.2. 1    25b Many find the perimeter of the sector OQR instead of just the shaded region. (Adding 17 instead of 12 and 11) 2  26a Generally well done. A few inverted the fractions and so got the wrong answer. 1  26b Some put 14 x 30 (distance = speed x time) instead of calculating area under graph. 2  A few used subtraction of area instead. 26c Generally poorly done. Only a few students calculated the instantaneous speed. Some students mistaken 26 m/s as the average speed. 2 