Sec 3 Maths

Lee012lee SG

For Sec 3 Maths students to practise,

Question 1

If the answer is 161 1/3, do we need to round off the answer to 3 sig fig ?

Question 2

If the answer is - 3/2, do we need to change it to - 1.5 or - 1 1/2 ?

Question 3

If the answer is x^7y^-1, do we need to change it to x^7 / y ?

Question 4

If the answer is a = cube root ((3V+4pi b^3) / 4 pi ), do we need to change it to a = cube root (3V /4pi + b^3) ?

Question 5

If the question asks for the y - intercept of the line l, should the answer be - 2 or (0, -2) ?

Question 6

If the answer is 8.1356 x 10^16, do we need to round it off to 8.14 x 10^16?

These questions arises out of 2012 O level E. Maths P1 and P2.

The incorrect answers to these questions can cost students more than one grade.

FireIce SG

if in fraction it is the most exact, no need to change to decimal and round off to 3sf
fraction can be in improper or mixed number as long as simplest form
change to equivalent decimal is accepted

-ve powers shd be changed to denominators with +ve powers

y-intercept is just the value of y, ( y = # ) , not a coordinate

standard form no need to round off to 3sf unless stated in qn

Lee012lee SG

For Sec 3 Maths students to practise,

Question 1

If the answer is 161 1/3, do we need to round off the answer to 3 sig fig ?

Answer to Question 1

We do not need to round the answer to 3 sig fig as the answer is an exact answer.

Question 2

If the answer is - 3/2, do we need to change it to - 1.5 or - 1 1/2 ?

Answer to question 2

Though improper fraction and mixed numbers are allowed, it is a good practice to leave the answer in mixed number or equivalent exact decimal ESPECIALLY when units are required ie the answer should be 1.5 metres or 1 1/2 metres, not 3/2 metres.

Question 3

If the answer is x^7y^-1, do we need to change it to x^7 / y ?

Answer to Question 3

We do need to change the negative indices to positive indices in the answer unless the question says that to leave the answer in index notation form.

Question 4

If the answer is a = cube root ((3V+4pi b^3) / 4 pi ), do we need to change it to a = cube root (3V /4pi + b^3) ?

Answer to Question 4

Both answers are acceptable, though the second answer is preferred.

Question 5

If the question asks for the y - intercept of the line l, should the answer be - 2 or (0, -2) ?

Answer to Question 5

The y-intercept of the line is - 2. The question did not ask for the co-ordinates of the point where the line cuts the y-axis.

Question 6

If the answer is 8.1356 x 10^16, do we need to round it off to 8.14 x 10^16?

Answer to Question 6

If the A is an exact decimal, we do not need to round off the answer to 3 sig fig. But if the A is not an exact decimal, we will need to round it off to 3 sig fig.

These questions arises out of 2012 O level E. Maths P1 and P2.

Thank you for your kind attention,

Regards

Lee012Lee