I need help. With this p

Mathematics

1 answer:

iogann1982 [59]3 years ago

6 0

$a_n=a_1+(n-1)d$ - the formula of n-th term of an arithmetic sequence.

We have:

$a_5=12.4;\ a_9=22.4$

$a_9-a_5=(9-5)d\to4d=22.4-12.4\\\\4d=10\ \ \ \ |:4\\\\d=2.5$

$a_{31}=a_9+(31-9)d\to a_{31}=22.4+22\cdot2.5=77.4$

Answer: C. 77.4

You might be interested in

Two certificates of deposit pay interest that differ by 3%. Money invested for one year in the first CD earns $240 interest. The

Soloha48 [4]

a = interest rate of first CD

b = interest rate of second CD

and again, let's say the principal invested in each is $X.

$\bf a-b=3\qquad \implies \qquad \boxed{b}=3+a~\hfill \begin{cases} \left( \frac{a}{100} \right)X=240\\\\ \left( \frac{b}{100} \right)X=360 \end{cases} \\\\[-0.35em] ~\dotfill\\\\ \left( \cfrac{a}{100} \right)X=240\implies X=\cfrac{240}{~~\frac{a}{100}~~}\implies X=\cfrac{24000}{a} \\\\\\ \left( \cfrac{b}{100} \right)X=360\implies X=\cfrac{360}{~~\frac{b}{100}~~}\implies X=\cfrac{36000}{b} \\\\[-0.35em] ~\dotfill\\\\$

$\bf X=X\qquad thus\qquad \implies \cfrac{24000}{a}=\cfrac{36000}{b}\implies \cfrac{24000}{a}=\cfrac{36000}{\boxed{3+a}} \\\\\\ (3+a)24000=36000a\implies \cfrac{3+a}{a}=\cfrac{36000}{24000}\implies \cfrac{3-a}{a}=\cfrac{3}{2} \\\\\\ 6-2a=3a\implies 6=5a\implies \cfrac{6}{5}=a\implies 1\frac{1}{5}=a\implies \blacktriangleright 1.2 = x\blacktriangleleft$

$\bf \stackrel{\textit{since we know that}}{b=3+a}\implies b=3+\cfrac{6}{5}\implies b=\cfrac{21}{5}\implies b=4\frac{1}{5}\implies \blacktriangleright b=4.2 \blacktriangleleft$

3 0

3 years ago

What is the period of the sinusoidal function

rodikova [14]

Answer:

The period of the sine curve is the length of one cycle of the curve. The natural period of the sine curve is 2π. So, a coefficient of b=1 is equivalent to a period of 2π. To get the period of the sine curve for any coefficient b, just divide 2π by the coefficient b to get the new period of the curve.

Step-by-step explanation:

3 0

2 years ago

Read 2 more answers

Write an exponential expression: choose an odd number between

Ronch [10]

Chicken nuggets and fries please

4 0

3 years ago

Read 2 more answers

Mr.marquez had 123 eggs in a refrigerator in his restaurant.he put 32 more cartons of eggs in the refrigerator each carton conta

Reil [10]