Answer:
a = 4.8
Step-by-step explanation:
9 - 4a + 12 = 6a - 27
21 - 4a = 6a - 27
48 - 4a = 6a
48 = 10a
a = 4.8
Well, since the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 6% of 80%, that means there is a 90% confidence interval. 9 / 10 = .90 = 90% 90% = 1.645 1.645 * .9 = 1.4805 Margin of Error - 1.4805and The margin of error is the distance from x-bar, the center of the confidence interval ,to the end of the interval. This distance is 6% of 80% which is given by: 80×6100=4.8 Therefore the margin of error is 4.8% and the confidence interval is: ({80 - 4.8}%, {80 + 4.8}%)
Your answer is 9.042÷2.1=4.305
Answer:
Step-by-step explanation:
Given
← factorise numerator and denominator
2x² - 18 ( factor out 2 from each term )
= 2(x² - 9) ← difference of 2 squares
= 2(x - 3)(x + 3)
and
x² + 4x - 21 = (x + 7)(x - 3) , then
= 
← cancel common factor (x - 3) on numerator/ denominator
=
