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secondary 2 | Maths
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I need help with question 8 and 9
Date Posted: 4 years ago
Views: 480
8a) Greatest value of x is 7 given that most number of students spend 1 hour on the computer each day (mode)
8b) mean is the sum of all hours divided by the number of students: so take 0x4 + 1x8 + 2x3 +3x5 +4x + 5x7=2.625 and solve for x
8c) Median would be the middle value (for (4+8+3+5+x+7)/2)
for x to be the smallest:
4+8+3=4+x+7
8b) mean is the sum of all hours divided by the number of students: so take 0x4 + 1x8 + 2x3 +3x5 +4x + 5x7=2.625 and solve for x
8c) Median would be the middle value (for (4+8+3+5+x+7)/2)
for x to be the smallest:
4+8+3=4+x+7
See 2 Answers
For part 9(b), the question says "hence …".
When question says "hence...", we MUST use the result from the preceding part.
When question says "hence or otherwise ...", then we need not use the result from the preceding part.
Even though the answers for 9(b) are correct here, likely no marks will be awarded because did not follow the question instruction.
Correct method should be …
from 9(a),
x^2 -6x+2=(x-3)^2-7
so,
x^2-6x+2=0 implies
(x-3)^2-7=0
(x-3)^2=7
x-3=+sqrt(7) or -sqrt(7)
x=+sqrt(7)+3 or -sqrt(7)+3
x=5.65 or 0.35 (to 2 d.p.)
When question says "hence...", we MUST use the result from the preceding part.
When question says "hence or otherwise ...", then we need not use the result from the preceding part.
Even though the answers for 9(b) are correct here, likely no marks will be awarded because did not follow the question instruction.
Correct method should be …
from 9(a),
x^2 -6x+2=(x-3)^2-7
so,
x^2-6x+2=0 implies
(x-3)^2-7=0
(x-3)^2=7
x-3=+sqrt(7) or -sqrt(7)
x=+sqrt(7)+3 or -sqrt(7)+3
x=5.65 or 0.35 (to 2 d.p.)
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