8th Class Mathematics Introduction to Graphs

  • question_answer 12)                 Draw the graphs for the following tables of values, with suitable scales on the axes.                
    Number of apples 1 2 3 4 5
    Cost (in Rs) 5 10 15 20 25
    (b) Distance travelled by a car                
    Time (in hours) 6 a.m. 7 a.m. 8 a.m. 9 a.m.
    Distances (in km) 40 80 120 160
      (i) How much distance did the car cover during the period 7.30 a.m. to 8 a.m.? (ii) What was the time when the car had covered a distance of 100 km since it's start? (c) Interest on deposits for a year.
    Deposit (in Rs) 1000 2000 3000 4000 5000
    Simple Interest (in Rs) 80 160 240 320 400
      (i) Does the graph pass through the origin? (ii) Use the graph to find the interest on Rs 2500 for a year. (iii) To get an interest of Rs 280 per year, how much money should be deposited?

    Answer:

                    (a)     Scale: Horizontal: 2 units = 1 apple Vertical: 1 unit = Rs 5 ? Mark number of apples on horizontal axis. ? Mark cost (in Rs) on vertical axis. ? Plot the points: (1, 5), (2, 10), (3, 15), (4, 20) and (5, 25) ? Join the points. We get a linear graph. (b)   Scale: Horizontal: 2 units = 1 hour Vertical: 2 units = 40 km ? Mark time (in hours) on horizontal axis. ? Mark distances (in km) on vertical axis. ? Plot the points (6 a.m., 40), (7 a.m., 80) (8 a.m., 120) and (9 a.m., 160). ? Join the points. We get a linear graph. (i) Distance covered during 7.30 a.m. to 8 a.m. = 120 km ? 100 km = 20 km (ii) The time when the car had covered a distance of 100 km since its start was 7.30 a.m. (c) Scale: Horizontal: 2 units = Rs 1000 Vertical: 2 units = Rs 80 ? Mark deposit (in Rs) on horizontal axis. ? Mark simple interest (in Rs) on vertical axis. ? Plot the points (1000, 80), (2000, 160), (3000, 240) (4000, 320) and (5000, 400). ? Join the points. We get a linear graph. (i) Yes ! The graph passes through the origin. (ii) Interest on Rs 2500 for a year = Rs 200 (iii) To get an interest of? 280 per year, Rs 3500 should be deposited.


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