Answer: Minimum sample size = 110
Step-by-step explanation:
Formula to find minimum sample size :
, where z = critical z-value for confidence level, s= sample standard deviation , E = margin of error
Given: E= 4 , s= 18
Critical z-value for 98% confidence = 2.327
So, 
Minimum sample size = 110
Answer:
x = 14/3 + sqrt(217)/3 or x = 14/3 - sqrt(217)/3
Step-by-step explanation:
Solve for x:
x + 4 + 1/x = (10 x)/7
Bring x + 4 + 1/x together using the common denominator x:
(x^2 + 4 x + 1)/x = (10 x)/7
Cross multiply:
7 (x^2 + 4 x + 1) = 10 x^2
Expand out terms of the left hand side:
7 x^2 + 28 x + 7 = 10 x^2
Subtract 10 x^2 from both sides:
-3 x^2 + 28 x + 7 = 0
Divide both sides by -3:
x^2 - (28 x)/3 - 7/3 = 0
Add 7/3 to both sides:
x^2 - (28 x)/3 = 7/3
Add 196/9 to both sides:
x^2 - (28 x)/3 + 196/9 = 217/9
Write the left hand side as a square:
(x - 14/3)^2 = 217/9
Take the square root of both sides:
x - 14/3 = sqrt(217)/3 or x - 14/3 = -sqrt(217)/3
Add 14/3 to both sides:
x = 14/3 + sqrt(217)/3 or x - 14/3 = -sqrt(217)/3
Add 14/3 to both sides:
Answer: x = 14/3 + sqrt(217)/3 or x = 14/3 - sqrt(217)/3
Answer:
6/5
Step-by-step explanation:
you multiply by 2
Answer:
128.67 feet
Step-by-step explanation:
We would be solving this question using the Trigonometric function of tan.
Tan( of the angle of elevation) = height of the tower ÷ height of the shadow.
Angle of elevation = 65°
Height of the tower = unknown, which is designated as X
Height of the shadow = 60 feet.
Therefore,
tan 65° = X/ 60 feet
We crossmultiply
X = tan 65° × 60 feet
X = 128.67041523 feet.
Approximately, X = 128.67 feet.
Therefore, the tower is 128.67 feet tall.
Answer:
Step-by-step explanation:
hope this helps
