Find the 20th term from the last term of the AP 3,8,13,......253

1.	Find the 20th term from the last term of the AP 3,8,13,......253
Answer» a child puts one 5 rupee coin of her saving in the piggy bank on the first day, 253=3+(n-1)×5n-1=250/5=50So n=51So 20th term from last is 51-20+1=32nd terma32=3+31×5=158 and \xa0a = 3, d = 5Now, 253 = a + (n + 1) d⇒ 253 = 3 + (n -1) x 5⇒ 253 = 3 + 5n – 5⇒ 5n = 253 + 2 = 255⇒ n = 255/5 = 51Therefore, 20th term from the last term = 51 – 19 = 32a32\xa0= a + 31d\xa0= 3 + 31 x 5= 3 + 155= 158Thus, required term is 158 a20=a+19d=3+19×5=98 The 20th term is 158 . 158 158

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