A chess club charges a joining fee of ₹200 plus ₹50 for every match played. The following table shows the amount a player will have to pay as the number of matches varies.
Step-by-step solution
To find: The amount paid for 1, 2, 3, … and m matches
Idea: The joining fee is fixed; only the match charge grows. For m matches the match charge is 50 × m.
- Amount = 200 + 50 × (number of matches):1 mark
Number of matches played 1 2 3 4 5 … m Amount paid (₹) 250 300 350 400 450 … 200 + 50m - So for m matches the total cost is ₹(200 + 50m). The highest power of m is 1, so 200 + 50m is a linear polynomial in m.½ mark
- Each extra match adds the same ₹50 (250, 300, 350, …). This constant increase is what makes the pattern linear.½ mark
Check: For 4 matches: 200 + 50 × 4 = 400, which matches the table ✓.
Answer to write in the exam
Amount = 200 + 50 × (number of matches)
1, 2, 3, 4, 5 matches → ₹250, ₹300, ₹350, ₹400, ₹450
Amount increases by ₹50 for every additional match
∴ For m matches, amount = ₹(200 + 50m), a linear polynomial in m
Common mistakes that cost marks
- Writing 250m (charging the joining fee for every match). The ₹200 is paid only once.
- Writing 200m + 50. Here the fixed amount and the per-match amount have been swapped.
- Forgetting the joining fee and writing 50m.
How this can come in the exam
A gym charges ₹500 to join and ₹120 per session. The cost of s sessions is
- ₹620s
- ₹(500s + 120)
- ₹(500 + 120s)
- ₹(500 + 120)s
Show answer
(C) ₹(500 + 120s)
Fixed ₹500 plus 120 for each of the s sessions: 500 + 120s.
A swimming club charges a registration fee of ₹300 and ₹40 per swim.
(i) Make a table of the amount paid for 1 to 4 swims. (ii) Write the amount for n swims. (iii) Is it a linear polynomial? Why? (iv) By how much does the amount increase for each extra swim?
Show answer
(i) 340, 380, 420, 460 (1 mark). (ii) ₹(300 + 40n) (1 mark). (iii) Yes: the highest power of n is 1 (1 mark). (iv) ₹40, the constant difference (1 mark).Try one yourself
A taxi app charges ₹60 booking fee and ₹18 per km. Write the fare for k km and find it for 12 km.
Show answer
₹(60 + 18k). For 12 km: 60 + 216 = ₹276.
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