Question

In a school , students decided to plant trees is and around the school to reduce air pollution. It was decided that number of trees, that each section of each class will plant will be double of the class in which in which they are studying . If there are 1 to 12 classes in the school and each class has two section find how many trees were planted by the student

Answer 1

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 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( 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
Sn = n/2[a + l ],
Sn = 12/2[ 4 + 48]
Sn = 6 × 52 = 312

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

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Answer 2

Answer:

Step-by-step explanation:

Solution :-

Number of plants planted by class 1 = 2 (class 1 × 2 sections)

= 2 × 1 × 2 = 4 tress

Similarly, number of plants planted by class 2 = 2 (class 2 × 2 sections)

= 2 × 2 × 2 = 8 trees

We now know, a = 4 and d = 4

Number of classes, n = 12

Total number of plants planed = Sum of AP = S₁₂

S(n) = n/2(2a + (n - 1)d)

⇒ S(n) = 12/2 + (2 × 4 + (12 - 1)4)

⇒ S(n) = 6(8 + 44)

⇒ S(n) = 6 × 52

⇒ S(n) = 312 trees

Hence, 312 trees were planted by the student.

Values :-

• Environmental friendly
• Social awareness
• Sense of responsibility towards the society.