The owner of a golf course wants to determine if his golf course is more difficult than the one his friend owns. He has 20 golfers play a round of 18 holes on his golf course and records their scores. Later that week, he has the same 20 golfers play a round of golf on his friend's course and records their scores again. The average difference in the scores (treated as the scores on his course - the scores on his friend's course) is 8.9 and the standard deviation of the differences are 11.986. Calculate a 99% confidence interval to estimate the average difference in scores between the two courses.

(1.985, 15.815)

Step-by-step explanation:

Given that:

Sample size (n) = 20

Standard deviation (s) = 11.986

Mean (m) = 8.9

α = 99%

Using the relation :

Confidence Interval = Mean ± Error

Where ;

Error = Zcritical * standard deviation / sqrt(n)

Zcritical at 99% = 2.58

Hence,

Error = 2.58 * (11.986/sqrt(20))

Error = 2.58 * 2.6801510

Error = 6.91478958

Hence,

Lower boundary = 8.9 - 6.91478958 = 1.98521042

Upper boundary = 8.9 + 6.91478958 = 15.81478958

(1.985, 15.815)

75 tickets have been sold so far.

step-by-step explanation:

in this question it is clearly mentioned that 45 children's tickets have been sold and this number is 60% of the total tickets sold.

now let's assume the total number of tickets sold be x.

then 60% of x = 45

⇒

⇒ x(.6) = 45

by dividing with .6 on both the sides of the equation

⇒ x = 75

therefore 75 tickets have been sold so far.

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2