sum of first 55 terms is 3300 find the 28th term
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[Given]: S55 = 3300
To find:- t28
Sn = n [2a + (n – 1)d]
2
S55 = 55 [2a + (55 – 1) d]
2
3300 = 55 [2a + 54d]
2
3300 = 55 x 2[a + 27d]
2
3300 = 55 [a + 27d]
3300/55 = a + 27d
a + 27d= 60 ..(i)
now, by using Formula,
tn=a+(n-1)d
t28=a+(28-1)d
t28=a+27d
t28=60 from (I)
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