In an arithmetic sequence:
Tn=t₁+(n-1)d
t₄=t₁+(4-1)d=t₁+3d
t₅=t₁+(5-1)d=t₁+4d
t₆=t₁+(6-1)d=t₁+5d
t₄+t₅+t₆=(t₁+3d) +(t₁+4d)+(t₁+5d)=3t₁+12d
Therefore:
3t₁+12d=300 (1)
t₁₅=t₁+(15-1)d=t₁+14d
t₁₆=t₁+(16-1)d=t₁+15d
t₁₇=t₁+(17-1)d=t₁+16d
t₁₅+t₁₆+t₁₇=(t₁+14d)+(t₁+15d)+(t₁+16d)=3t₁+45d
Therefore:
3t₁+45d=201 (2)
With the equations (1) and (2) we make an system of equations:
3t₁+12d=300
3t₁+45d=201
we can solve this system of equations by reduction method.
3t₁+12d=300
-(3t₁+45d=201)
-----------------------------
-33d=99 ⇒d=99/-33=-3
3t₁+12d=300
3t₁+12(-3)=300
3t₁-36=300
3t₁=300+36
3t₁=336
t₁=336/3
t₁=112
Threfore:
Tn=112+(n-1)(-3)
Tn=112-3n+3
Tn=115-3n
Now, we calculate T₁₈:
T₁₈=115-3(18)=115-54=61
Answer: T₁₈=61
D
uses the the formula y=mx+b and m is the slope. b is the y intercept.
Answer:
1.5 meters
Step-by-step explanation:
We know that the sum of all of the data in a set = average * number of data.
Therefore, the sum of the first 10 is 1.5 * 10 = 15 meters, the sum of the second 10 is 1.48 * 10 = 14.8 meters and the sum of the last 2 is 1.6 * 2 = 3.2 meters for a total of 15 + 14.8 + 3.2 = 33 meters. This means that the mean is 33 / 22 = 1.5 meters.
Step-by-step explanation:
The formula is Distance=√(x2-x1)²+(y2 -y1)²
x1 is 5, x2 is 1, y1 is 9, y2 is 6
D = √( 1-5)² +(6-9)²
D = √(-4)²+(-3)²
D = √16+9
D = √25
D = 5 units
Answer: 
Step-by-step explanation:
The confidence interval for population mean is given by :-
, where 
is the sample proportion, n is the sample size , 
is the critical z-value.
Given : Significance level : 
Sample size : n= 85
Critical value : 
Sample proportion: 
Now, the 99% confidence level will be :
Hence, the 99% confidence interval estimate of the true proportion of families who own at least one DVD player is
