Question

15 students planted 18 trees in a day how many students need to the plant in 30 trees​

Answer 1

Step-by-step explanation:

According to the question , there are two sections of each class so the number of trees that are planted by students of class I, class II, class III, …..& class XII are:

Number of trees planted by the students of two sections of class I=2×2=4

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

Similarly,

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

Number of trees planted by the students of two sections of class12=2×24=48

So, the number of trees planted by the students of two sections of different classes are4,8,12,……48

This series forms an AP

Here,first term(a)=4, common Difference (d)=8–4=4, last term (l)=48 and (number of terms)n=12

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

S

n

=

2

n

[a+l],

S

n

=

2

12

[4+48],

S

n

=6×52=312,

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

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