<span>We have to find the product : ( 9 t - 4 ) ( - 9 t - 4 ) = - ( 9 t - 4 ) ( 9 t + 4 ) After that we can use the difference of squares. The formula is: ( a + b ) ( a - b ) = a^2 - b^2. In this case: - ( 9 t - 4 ) ( 9 t + 4 ) = - ( 81 t^2 - 16 ) = - 81 t^2 + 16 . Answer: B ) - 81 t^2 + 16.</span>
Answer:
67 years old. (you only gave 4 people and missed out one person)
Step-by-step explanation:
take all the ages first and put the unknown (age of the person who entered the room) as x.
14, 16, 16, 13, x
all of these numbers added to together would be:
59 + x
Because the question is talking about the mean age, to find mean:
add all the values in the data (ages) and divide by the total number of values on the list. (in your case would be 6 people (following your question) but you gave only 5 people including the x).
then (59 + x) / 6 = 21
21 x 6 = 126
126 = 59 + x
x = 67
Answer:
67.0
Step-by-step explanation:
Answer:
3/8 for the second question
Step-by-step explanation:
number of shaded portion on total number
First, arrange the data in a table for easy reference:
x y
20 50
30 45
45 55
60 70
80 80
90 90
45 80
120 100
90 95
70 85
Then, use the calculator to find the relationship of the two variables, x (minutes studied) and y (test scores)
The equation is
y = 0.56686x + 38.15
