Multiple Choice Questions
Short Answer Type
Long Answer TypeThe sum of the 2nd and the 7th terms of an AP is 30. If its 15th term is 1 less than twice its 8th term, find the AP.
In a school, students decided to plant trees in and around the school to reduce air pollution. It was decided that the number of trees, that each section of each class will plant, will be double of the class in which they are studying. If there are 1to 12 classes in the school and each class has two sections, find how many trees were planted by the students. Which value is shown in this question?
Short Answer TypeLong Answer TypeIf the ratio of the sum of the first n terms of two A.Ps is (7n + 1) : (4n + 27), then find the ratio of their 9th terms.
Multiple Choice QuestionsLong Answer TypeFind the sum of all three digit natural numbers, which are multiples of 7.
First three-digit number that is divisible by 7 = 105
Next number = 105 + 7 = 112
Therefore the series is 105, 112, 119,........
The maximun possible three digit number is 999.
When we divide by 7, the remainder will be 5.
Clearly, 999 - 5 = 994 is the maximum possible three-digit number divisible by 7.
The series is as follows:
105, 112, 119,.........994.
Here a = 105, and d = 7
Let 994 be the nth term of this A.P.
an = a + ( n-1 ) d
994 = 105 + ( n-1 ) x 7
( n-1 ) x 7 = 889
( n-1 ) = 127
n = 128
So, there are 128 terms in the A.P.
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