In an arithmetic sequence, the sum of the first n terms is s_n=n^2. find a_8

Mathematics

1 answer:

Julli [10]2 years ago

4 0

Answer:

$a_{8} = 15$

Step-by-step explanation:

$a_{1} + a_{2} + ..... + a_{7} + a_{8} = 8^{2} = 64$

$-a_{1} - a_{2} ..... - a_{7} = - 7^{2} = -49$ Now add the two equations

$a_{8} = 64 - 49 = 15$

$a_{8} = 15$

You might be interested in

What is the value of x? 36 Degrees, Tangent lines, Acellus, Geometry

GrogVix [38]

Answer:

x=54

Step-by-step explanation:

since the line opposite of x is tangent to the circle, the angle made but the point is 90 degrees, so then you add 90 and 36 and subtract that by 180 to get the other angle.

4 0

3 years ago

In a survey, 24 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped

erica [24]

Answer:

The 98% confidence interval for the mean amount spent on their child's last birthday gift is between $40.98 and $43.02.

Step-by-step explanation:

We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 24 - 1 = 23

98% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 23 degrees of freedom(y-axis) and a confidence level of $1 - \frac{1 - 0.98}{2} = 0.99$ . So we have T = 2.5