Math, asked by anuragjain8731, 11 months ago

Sum of first 55 terms in an A.P. is 3300,find it's 28th term​

Answers

Answered by pankaj36936
8

therefore 28th term of A. P is 60

Attachments:
Answered by Anonymous
6

Answer:-

 \boxed{ \bf{t_{28} = 60}}

Step - by - step explanation :-

To find :-

Find 28th term of the given AP.

Given :-

55th term is 3300.

Solution:-

Let first term of this AP is "a"

Common difference is "d"

According to the question-

  \:  \bf{s_{55} = 3300} \\  \\ \bf{  \frac{55}{2}  \bigg(2a + (55 - 1)d \bigg) = 3300} \\  \\   \bf{\frac{55}{2}  \bigg(2a + 54d \bigg) = 3300} \\  \\ \bf{ 55(a + 27d) = 3300} \\  \\  \bf{a + 27d \:  = 60 }\:  \:  \: ......(1)

And also ,

We know that,

 \bf{t_{28} \:  = a \:  + (28 - 1)d} \\  \\ \bf{ t_{28} \:  = a + 27d \: } \: ......(2)

On comparing eq (1) and (2)

We get,

  \boxed{ \red{\bf{t_{28} = 60}}}

Hope it helps you.

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