An arithmetic sequence has first term 9 and common difference 3. What is the sum of its first 9 terms?
Answer and explanation
Correct answer: D.
- Step 1: The 9-th term is . Step 2. Sum . **Answer: . Why not the others:** gives the last term only; doubles the difference part; drops part of the last term.
Practise more Geometry, sequences and probability.
Free questions with an explanation for every one, and full timed Egzamin Maturalny (Matura Poland) mock tests.
More Geometry, sequences and probability questions
- The price of a tablet is 200. It is first increased by 40% and then the new price is decreased by 40%. What is the final price?
- 20% of a number is 12. What is the number?
- The mean of 7 numbers is 66. Of them, 6 are 59, 60, 66, 59, 54, 72. What is the remaining number?
- What is the difference between the compound interest and the simple interest on 2500 for 2 years at 6% per year (compounded annually)?
- A rectangle has length 10 cm and width 10 cm. A square of side 2 cm is cut from one corner. What is the area of the remaining shape, in cm…
- A right triangle has legs of length 20 and 48. What is the length of its hypotenuse?