For question 3 you didn’t know that the principal is the starting amount. You calculated what €976.70 would amount to after 6 years at 4.5% interest. So you said:

Start (principal): €976.70

End: €1,271.92

while the question asked what principal would amount to €976.70:

Start (principal): ???

End: €976.70

At the very least your answer should have been less than €976.70. To do this properly you say let be the principal that amounts to €976.70. Therefore satisfies the equation:

Solving this equation for gives you the solution.

For question 4 you just did

…

What you had was

.

The way I recommended that ye do these was as follows. Know that

.

Therefore

.

For question 5… I have no idea what you actually did wrong. If you wrote sohcahtoa you would note that

and you could solve for .

For question 6 you assumed that all of the sides had the same length. This is only true for triangles where all angles are . In fairness you made a good effort after this but you know… MCQ. What you needed to do was use

on the top wedge of the triangle.

For question 6 you have an even number of numbers:

.

The median separates the numbers into big and small:

.

With an even number of terms you take the average of the two middle numbers so you should have gotten 10. You said 11.

For question 8… well question 8 was a little harder. Your attempt made no sense. Four of five numbers are 162, 183, 119 and 218. You calculated

.

I have no idea why. You either let be the fifth number and solve

Or else use the alternative method (see the top of page 72 of the notes).

For question 9. You started well with:

.

After this you did something which makes no sense. You ‘moved’ some symbols around. Perhaps this question is tough because we are only properly doing equations now (although I did talk about these principles earlier in the year)… see in class now how we would deal with this.

m,

because is positive.

For question 10 you calculated the area when you were asked to calculate the perimeter.

For question 11. (i) you lost a half mark for not giving your answer correct to the nearest whole number. For part (ii) you failed completely to apply the definition of sine. What you should have had was

,

to which you can apply to both sides. Instead you calculated

… this is just sine of which has nothing to do with the question.

You lost a mark in question 11 because you found the area of the whole circle when there was only a semi-circle.

In question 13 — where you clearly put in work — you lost half a mark for not giving your answer correct to two decimal places.

That is twice you lost marks for not reading the questions properly.

Regards,

J.P.

What questions did I get wrong?

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