## Friday, February 18, 2011

### Error Analysis 1 - Chapter 1

The following are the work done by your friends.
Please identify the nature of the errors committed and

1. Student A and B both need workings,while students C's first working is wrong.

2. Student A) No working
Student B) 0.03 squared is actually 0.0009
Student C) 0.05 converted to fraction is 1/20

3. For student C, the error is 1/4+1/400=1/404. The correct answer should be 1/4+1/400=100/400+1/400
=101/400

4. Student A......never write down the necessary steps to show how you get the final answer.
Student B......the working must be shown in a number sentence
Student C......should not do the steps separately

5. This comment has been removed by the author.

6. Student A: Should take away the brackets and distribute the numbers then add them together to avoid carelessness.
Student B: Should put down the 0.008 and 0.000027 after the equals sign, so even if he/she makes a mistake in calculation, maybe his/her teacher can still give him marks for his workings.
Student C: In the last step, the denominators of both the factors should be the same for addition of fractions.

7. For Student A and B, he/she did not list out the complete workings of the question, and for student C, his/her workings are done wrongly

8. sorry for student c the last step is wrong

9. Student A did not show any working.

Student B has incomplete working.

Student C didn't show working for 1/4.

10. PS, i forgot to add in something.

Student A 's work does not have any working, writing the answer straight away.
Student B's work shows some working but not in the correct form.
Student C's work shows the correct working but there are 2 'equal' signs together on the same line.

11. Student A:He did not separate his answers to express them clearly and thus the answer is wrong.
Student B: He cubed 0.03 instead of squaring it.
Student C:He changed the decimal to fraction from 0.05 to 1/2 and he did not put the answer next to the question also,he added the denominators and thus the answer was wrong.

12. Student A:No working
Student B:answer moved down a few decimals
Student C:working error

13. Student A: Never simplify the square roots and its contents. Just use the calculator to press out the answer.

Student B: When writing out the equations, should have done 0.008-0.000027=0.007973. Should not have drawn the arrows.

Student C: Cannot just add the denominator must make the denominator equal first than

14. Student A-
Did not show his/her working.He just write the answer from his/her calculator.
Student B-Although he/her shown the simplified but he should also show the working like 0.008-0.000027=0.007973.
Student C-
Although he did it in the correct way, but his answer is wrong ! It should be 101/400

15. For student A,he did not show any workings.As for student B, 0.03x0.03 is not equal to 0.000027 but it is 0.00009

16. Student A:His calculations are wrong and the final answer is 81 instead of 18225.
Student B:His calculation of (0.03)2 is wrong, it is not 0.000027, but is 0.0009.
Student C: His last working, 1/4+1/400 is not equal to 1/404, but is equal to 101/400.

17. For student A,his final answer is wrong and it should be 81.
For student B,his calculation for (0.03)squared is wrong as it should be 0.0009,which resulted in the entire calculation wrong.
For student C,when 1/4 is added to 1/400,the answer would be 101/400 and not 1/404

18. Student A: no workings
Student B: (0.03)^2 is not equal to 0.000027.
Student C: he/she didn't change the fractions to the same denominator.

19. Student A : No workings were shown, the last answer was also wrong.
Student B :He probably accidentally calculated (0.03)2 as (0.03)3 instead.
Student C :The last step should be 101/400 instead.

20. Student A did not show the working of how he/she got the answer. His answer is also wrong.

Student B did not show the proper working.

Student C did not show the steps (the equal sign =) of the number statement

21. Student A did not show the workings. His answer is also wrong.

Student B 0.03^2 is not equals to 0.000027, but 0.0009.

Student C: 1/4+ 1/400=101/400 and not 1/404

22. Student A did not show any working and his ans is also wrong.

Student B he squared (0.03)^2 wrongly

student C 0.2 does not equal to half

23. Student "A" didn't simplify the equation and then answer the question.

Student "B" didn't simplify the equation correctly.

Student "C" didn't join all of his working's together and the answer is supposed to be 101/400
(0.05)^2+(1/2)^2
=(5/100x5/100)+(1/2x1/2)
=25/10000+1/4
=1/400+1/4
=101/400

24. student A did not do working.

student B workings was wrong.