In the pattern 1/3 + 1/4 + 1/5 + ……. which fraction makes the sum greater than 1 (first time)? Explain.

Solution:

Given

1/3 + 1/4 + 1/5 + …….

Case 1 - 1/3 + 1/4 + 1/5 = (20 + 15 + 12)/60 = 47/60

Which is less than 1

Case 2 - 1/3 + 1/4 + 1/5 + 1/6 = (20 + 15 + 12 + 10)/60 = 57/60

Which is less than 1

Case 3 - 1/3 + 1/4 + 1/5 + 1/6 + 1/7 = (140 + 105 + 84 + 70 + 60)/420 = 459/420

Which is greater than 1

Therefore, 1/7 makes the sum greater than 1.

✦ Try This: In the pattern 1/2 + 1/3 + 1/4 + ……. which fraction makes the sum greater than 1 (first time)? Explain.

☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 2

NCERT Exemplar Class 7 Maths Chapter 2 Exercise Problem 125

In the pattern 1/3 + 1/4 + 1/5 + ……. which fraction makes the sum greater than 1 (first time)? Explain.

Summary:

In the pattern 1/3 + 1/4 + 1/5 + ……. The fraction 1/7 makes the sum greater than 1 (first time)

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