Question 2 (Page number 11) - Estimating value of expression (Page number 11) - Chapter 1 Class 7 - Large Numbers Around us (Ganita Prakash)

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Question 2 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 14,63,128 – 4,90,020 Roxie: “The difference is near 10,00,000 and is less than 10,00,000.” Estu: “The difference is near 9,00,000 and is more than 9,00,000.” (a) Are these estimates correct? Whose estimate is closer to the difference?For accurate estimates, we could round off numbers to nearest ten thousand or nearest thousand Let’s estimate nearest ten thousand For 14,63,128, we round down 63,128 to 63,000 ∴ 14,63,128 → 14,63,000 For 4,90,020, we round down 99,020 to 00,000 ∴ 4,90,020 → 4,90,000 Estimated difference = 14,63,000 – 4,90,000 = 9,73,000 Now, our statements are Roxie: “The difference is near 10,00,000 and is less than 10,00,000.” Estu: “The difference is near 9,00,000 and is more than 9,00,000.” Roxie said: “Near 10,00,000 but less” ✅ Correct Estu said: “Near 9,00,000 but more” ❌ Incorrect Roxie is closer, because 9,73,108 is close to 10,00,000, not 9,00,000 Question 2 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 14,63,128 – 4,90,020 Roxie: “The difference is near 10,00,000 and is less than 10,00,000.” Estu: “The difference is near 9,00,000 and is more than 9,00,000.” (b) Will the difference be greater than 9,50,000 or less than 9,50,000? Why do you think so?Our Estimated difference = 9,73,000 So, its greater than 9,50,0000 Question 2 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 14,63,128 – 4,90,020 Roxie: “The difference is near 10,00,000 and is less than 10,00,000.” Estu: “The difference is near 9,00,000 and is more than 9,00,000.” (c) Will the difference be greater than 9,63,128 or less than 9,63,128? Why do you think so?Our Estimated difference = 9,73,000 It seems greater than 9,63,128 Question 2 (Page number 11) Roxie and Estu are estimating the values of simple expressions. 14,63,128 – 4,90,020 Roxie: “The difference is near 10,00,000 and is less than 10,00,000.” Estu: “The difference is near 9,00,000 and is more than 9,00,000.” (d) Exact value of 14,63,128 – 4,90,020 = __________Difference = 14,63,128 − 4,90,020 = 9,73,108 Thus, actual difference is greater than 9,63,128