F.1 Maths Questions!

Q1 Let x questions correctly , 5x marks will be given
then (16 - x) questions are wrong , 3(16 - x) marks will be deducted.So5x - 3(16 - x) = 565x - (48 - 3x) = 565x - 48 + 3x = 568x = 104x = 13He answered 13 questions correctly.
Q2 The value of x after an increase of 40%
= x(1 + 40%)The sum of the value of x after a decrease of 10% and 2500
= x (1 - 10%) + 2500Sox (1 + 40%) = x (1 - 10%) + 2500
1.4x = 0.9x + 2500
0.5x = 2500
x = 5000The value of x after a decrease of 20% = 5000 (1 - 20%) = 5000 * 0.8= 4000

1) from the question, since it mentioned that no mark will be get /lose for unanswered questions, i.e. the four questions that had not been answered,will not affect the mark.

56 marks is only due to the correct and wrong answer.

there are totally 16 questions being answered,
let x be the number of questions that were answered correctly,
（16-x) will be those were wrong

marks gained from correct answers=5·x
marks lose from wrong answers =3·(16-x)

therefore,the final 56 marks =marks gained-marks lost
56= 5x-3·(16-x)
56=5x-48+3x
104=8x
∴ x=13
therefore,number of correct answer is 13, and number of wrong answer is3


2) a) value of x after an increase of 40%=x·(1+40%)=1.4x

b)sum of value of x after a decrease of 10% and 2500= x·(1-10%)+2500
=0.9x+2500
we need to use a) and b) to find the value of x first, then find
the value of x after a decrease of 20%

as a)=b) , i.e. 1.4x=0.9x+2500
0.5x=2500
i.e. x=5000

therefore, the value of x after a decrease of 20%= 5000·(1-20%)
=5000·0.8
=4000