my average results from the last 4 maths exams was 18 out of 25.what mark do i need in my fifth exam in order to increase the everage by 3%
Your average was 18/25 = 72% and you want to raise it to 75%. You need a grade x (in percent) such that
4*72 + x = 5*75
x = 5*75 - 4*72 = 87
An average of 18 out of 25 is 72%. I need to increase that by 3% to 75% by the time the marks from my final exam are included. Each exam is scored out of 25. Then so far I've got 72% out of a possible 100 marks, which is 72 marks. I need to get 75% overall by the time I've taken the fifth exam, which means I need to get a total of 75% x (5x25) = 93.75 marks. I've got 72 of them so far, so I need another 93.75 - 72 = 21.75 marks, which is 87%. (Note that I've assumed that every exam is scored out of the same number of marks: if they're not, then this calculation wouldn't work.)
To determine the mark you need to achieve in your fifth exam in order to increase your average by 3%, we first need to find your current average score.
To calculate your average, add up your scores from the last 4 exams and divide the total by 4:
(18 + 18 + 18 + 18) / 4 = 72 / 4 = 18
Your current average score is 18 out of 25.
Next, we need to find your desired average score. To increase your average by 3%, we'll first calculate 3% of 25:
(3 / 100) * 25 = 0.03 * 25 = 0.75
Adding 0.75 to 25 gives us:
25 + 0.75 = 25.75
So, your desired average score is approximately 25.75 out of 25.
To find the mark you need to achieve in your fifth exam, we'll set up an equation and solve for the unknown mark (let's call it "x"):
(18 + 18 + 18 + 18 + x) / 5 = 25.75
Multiplying both sides by 5:
18 + 18 + 18 + 18 + x = 25.75 * 5
72 + x = 128.75
Subtracting 72 from both sides:
x = 128.75 - 72
x = 56.75
Therefore, you would need to score approximately 56.75 out of 25 in your fifth exam in order to increase your average by 3%. However, since scores are typically out of 100, you may want to convert your result into a percentage by dividing it by 25 and multiplying by 100:
(56.75 / 25) * 100 = 227
So, you would need to score approximately 227 out of 100 (or 227%) in your fifth exam to increase your average by 3%.