Sequences and S...

I thought of a decimal number. After I had multiplied it by 2, then added 1.5 and then divided by 3, I got 3.5. What was the decimal number? 

If $$\displaystyle t_{3}=15,S_{10}=120$$ then the tenth term of the series i:

How many numbers are there between 500 and 600 in which 9 occurs only once?

Answer the following set of questions by reading the above pitctograph. Number of TV sets sold in the year 2005 is

If there are five consecutive integer in a series and the first integer is $$1$$, what is the value of the last consecutive integer?

Find a wrong  number in the series: 7, 28, 63, 124, 215, 342, 511

Which of the following is a geometric sequence?

$$10,$$ __$$, 15, 15, 20, 20, 25, 25,...$$. What number should fill the blank?

$$2, 3, 6, n, 42, . . .$$
Find the value of $$n$$ in the above series.

A ______ is the sum of the numbers in a geometric progression.