An arithmetic sequence has first term 9 and common difference 6. What is the sum of its first 18 terms?
Answer and explanation
Correct answer: D.
- Step 1: The 18-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 Mixed problems.
Free questions with an explanation for every one, and full timed SEE (Secondary Education Examination, Nepal) mock tests.
More Mixed problems questions
- The price of a sofa is 800. It is first increased by 25% and then the new price is decreased by 10%. What is the final price?
- 75% of a number is 225. What is the number?
- The mean of 4 numbers is 81. Of them, 3 are 93, 88, 90. What is the remaining number?
- What is the difference between the compound interest and the simple interest on 4000 for 3 years at 8% per year (compounded annually)?
- A rectangle has length 14 cm and width 7 cm. A square of side 1 cm is cut from one corner. What is the area of the remaining shape, in cm…
- A right triangle has legs of length 12 and 16. What is the length of its hypotenuse?