(b) In a "Double Your Money" quiz game, contestants get $5 for answering the first question correctly, then a further $10 for the second question, then a further $20 for the third, and so on for each question until they answer a question wrong.

(i) Jordan received $155 from the game. How many questions did he get right?

(ii) Charlotte answered 10 questions correctly. How much did she receive from the game?

(iii) Write a formula for the total amount received by a contestant who correctly answers n questions.