Hello :
<span>the general term equation, an, for the arithmetic sequence is :
An = A1+d(n-1)
A1 : the first term and : d the common diference
in this exercice :
A1 = 9
d =(-3)-(1) =(1)-(5) =(5) -(9) = -4
An = 9-4(n-1)
An = -4n +13</span>
The answer is D. 18.5
How? Because you have the numbers in order and cross the out it leaves you with 17, and 20 and the number between can be 19 or 18.5.
Hope I helped
Mark as brainliest?
Answer:
50 minutes.
Step-by-step explanation:
We solve this question by proportions, using rule of three.
One hour is 60 minutes.
5/6 hour
This is:

50 minutes.
X=8 I’m not that to sure but hope i helped!
Answer:
H0: μd=0 Ha: μd≠0
t= 0.07607
On the basis of this we conclude that the mean weight differs between the two balances.
Step-by-step explanation:
The null and alternative hypotheses as
H0: μd=0 Ha: μd≠0
Significance level is set at ∝= 0.05
The critical region is t ( base alpha by 2 with df=5) ≥ ± 2.571
The test statistic under H0 is
t = d/ sd/ √n
Which has t distribution with n-1 degrees of freedom
Specimen A B d = a - b d²
1 13.76 13.74 0.02 0.004
2 12.47 12.45 0.02 0.004
3 10.09 10.08 0.01 0.001
4 8.91 8.92 -0.01 0.001
5 13.57 13.54 0.03 0.009
<u>6 12.74 12.75 -0.01 0.001</u>
<u>∑ 0.06 0.0173</u>
d`= ∑d/n= 0.006/6= 0.001
sd²= 1/6( 0.0173- 0.006²/6) = 1/6 ( 0.017294) = 0.002882
sd= 0.05368
t= 0.001/ 0.05368/ √6
t= 0.18629/2.449
t= 0.07607
Since the calculated value of t= 0.07607 does not falls in the rejection region we therefore accept the null hypothesis at 5 % significance level . On the basis of this we conclude that the mean weight differs between the two balances.