Question

The class is asked to plant saplings all along the boundary of their school playground.The saplings are to be planted 40cm apart.How many saplings will we required given the playground is 60m long and 20m wide.

Answer 1

Answer:

Number of trees planted by the students of two sections of class | = 2x 2= 4

Number of trees planted by the students of two sections of class II = 2 x 4 = 8

Similarly,

Number of trees planted by the students of two sections of class 3 = 2 x 6 = 12

Number of trees planted by the students of two sections of class 12 = 2 × 24 = 48

So, the number of trees planted by the students of two sections of different classes are 4, 8, 12, 48

This series forms an AP

Here,first term( = 4, common Difference (d)

= 8 - 4 = 4, last term (1)= 48 and (number of

terms)n = 12

Number of trees planted by the students = sum of 12 terms of above AP

Sn = n/2[a + 1],

Sn = 12/2[ 4 + 48]

Sn = 6 x 52 = 312

Hence, the total number of trees planted by the students is 312.

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