# Ex 15.1, 3 - Chapter 15 Class 8 Introduction to Graphs

Last updated at July 24, 2018 by Teachoo

Last updated at July 24, 2018 by Teachoo

Ex 15.1, 3 For an experiment in Botany, two different plants, plant A and plant B were grown under similar laboratory conditions. Their heights were measured at the end of each week of 3 weeks. The results are shown by the following graph. (a) How high was a plant A after (i) 2 weeks? (ii) 3 weeks? (i) Height of plant A after 2 weeks = 7 cm (ii) Height of plant A after 3 weeks = 9 cm (b) How high was a plant B after (i) 2 weeks? (ii) 3 weeks? (i) Height of plant B after 2 weeks = 7 cm (ii) Height of plant B after 3 weeks = 10 cm (c) How much did the plant A grow during the 3rd week? Height of plant A gained during 3rd week = Height after 3rd week − Height after 2nd week = (9 − 7) cm = 2 cm (d) How much did Plant B grow from the end of the 2nd week to the end of the 3rd week?Required height = Height of plant B after 3rd weak − Height of plant B after 2nd week = 10 cm − 7 cm = 3 cm ∴ Plant B has grown 3 cm (e) During which week did Plant A grow most?Plant A grows most between Week 1 and Week 2 i.e. during the 2nd week. (f) During which week did Plant B grow least? Plant B grows least between Start and Week 1 i.e. during 1st week. (g) Were the two plants of the same height during any week shown here? Specify.Yes, at the end of 2nd week both plants were of 7 cm