Chapter 2
Introduction to Linear Polynomials
CBSE Class 9
Mathematics Solutions
Educart Mathematics class Class 9 NCERT Exemplar cover
Question:

What amount is left on the 15th15^{\text{th}} day? How many days to spend the entire amount (Refer to Example 7 on NCERT page no. 22)?                                                                                                                                                                         [Page No. 23]

Answer: Verified

The amount left on the nthn^{\text{th}} day is 100−5n100 - 5n.

• 15th15^{\text{th}} day: 100−5×15=100−75=₹25100 - 5 \times 15 = 100 - 75 = \text{₹} 25 left.

• Entire amount spent means the amount left is 0: 100−5n=0→5n=100→n=20100 - 5n = 0 \rightarrow 5n = 100 \rightarrow n = 20.
So it takes 20 days.

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(All Q's of this Chapter solved)
More NCERT Questions
What is the cost of travelling 15 km? For how many km will the cost be ₹ 700 (Refer to Example 9 on NCERT page no. 24)? [Page No. 24] Differentiate between the graphs of the equations y = 3x + 1, and y = -3x + 1. [Page No. 33] Identify other points on the line by completing the following table. [Page No. 28] x 1 2 5 7 9 12 20 y 3 15 Can you guess what the numbers 20 and 150 in the equation y = 20x + 150 represent (Refer to Example 11 on NCERT page no. 26)? [Page No. 27]