The top 15% (85th percentile) is the cutoff value
such that
where
is the corresponding cutoff for the standardized normal distribution. We have
, and so
Answer:
A) -2 - i√3 , -2 + i√3
Step-by-step explanation:
Solve using quadratic formula
x² + 4x + 7 = 0
The Almighty Formula
= -b ± √b² - 4ac/2a
Where ax + bx² + c = 0
From the above question
a = 1, b = 4, c= 7
Hence,
-4 ± √4² - 4 × 1 × 7/2 × 1
-4 ± √16 - 28/2
=( -4 ± √-12)/2
Since
b² - 4ac < 0
We have two complex roots
Simplifying
( -4 ± √-12)/2
= -4/2 ± √-12/2
= -2 ± 2√3i/2
= -2 ± √3i
Therefore,
-2 - √3i , -2 + √3i
or
-2 - i√3 , -2 + i√3
Option A , is the correct answer
Answer:
C. 4 weeks
Step-by-step explanation:
Trish and Aria are walking to raise money for the school library. Trish has walked 38 miles and walks 10 miles each week. Aria has walked 30 miles and walks 12 miles each week
After how many weeks will Trish and Aria have walked the same number of miles? A. 2 weeks B. 3 weeks C. 4 weeks D. 5 weeks
Trish = 38 + 10x
Aria = 30 + 12x
Where,
x = number of weeks
After how many weeks will Trish and Aria have walked the same number of miles?
Equate both equations
38 + 10x = 30 + 12x
38 - 30 = 12x - 10x
8 = 2x
x = 8/2
x = 4 weeks
