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You will need the equation:
Area = (a+b)/2 x h
Substitute the values in:
Area = (5 + 29)/2 x 10
You will get your answer as:
Area = 170
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The 10 girls in the class get a mean mark of 70%.
The 15 boys in the class get a mean mark of 80%.
Nick says that because the mean of 70 and 80 is 75 then the mean mark for the whole class in the test is 75%. Nick is not correct.
Is the correct mean less than or greater than 75%?
You must justify your answer.
This is the way I do it to find the average.
10 girls times 70 = 700
15 boys times 80= 1200
700+1200=1900 all their scores
1900÷25 (number of boys and girls)=76 or 76%
Nick's statement is incorrect because he has averaged the mean scores, not the total scores. The correct mean score for the combined class is 76%, which is greater than 75%.
The subject of this question is Mathematics, particularly focused on the concept of averages or mean. This question is asking about the combined average (mean) percentage score for a class test. Nick's statement is incorrect because he has simply taken the mean of the girls' mean score and the boys' mean score.
Here's the correct way to find the mean: Multiply the mean score of the girls by the number of girls, then do the same for the boys. Then sum those numbers up and divide by the total number of students. Let's calculate:
Therefore, the mean score for the whole class is 76%, which is greater than 75%.
#SPJ2
B. (9x^2 + 1)(9x^2 – 1)
C. (3x^2 + 1)^3(3x – 1)
D. (9x^2 + 1)(3x + 1)(3x – 1)
Using this: a²-b²=(a+b)(a-b)
81x^4-1=
(9x²)²-1=
(9x²-1)(9x²+1)= (in the bold half we use the formula again)
(3x+1)(3x-1)(9x²+1)
So the answer is D