Case-Study4 marksYear: 2024MediumCBSE Class 10
arithmetic-progressionsnth-termcase-study
Question
Treasure Hunt is an exciting and adventurous game where participants follow a series of clues/numbers/maps to discover hidden treasures. Players engage in a thrilling quest, solving puzzles and riddles to unveil the location of the coveted prize.
While playing a treasure hunt game, some clues (numbers) are hidden in various spots collectively forming an A.P. If the number on the nth spot is 20+4n, then answer the following questions to help the players in spotting the clues:

(i) Which number is on first spot?
(ii) (a) Which spot is numbered as 112?
**OR**
(ii) (b) What is the sum of all the numbers on the first 10 spots?
(iii) Which number is on the (n−2)th spot? Solution
1
(i) Number on first spot =20+4×1=24
+1 mark2
(ii)(a) 20+4n=112⇒4n=92⇒n=23
+2 marks3
(iii) Number on (n−2)th spot =20+4(n−2)=12+4n
+1 mark