Question

Examples For Practice
(A): Q.1) What is the sum of all odd numbers from 11 to 60 ?
(1) 905
(2) 875
(3) 955
(4) 845
1 to 702
explain with forMyla and step by step
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Answer 1

Answer:

you will have to use arithmetic progressions for this

Step-by-step explanation:

here our ap(ap=arithmetic progression) is

11,12,13.....60

in this Ap , a=11 , d=1 , n = 49 , Sn = ?

a = first digit of the ap

d = common difference i.e. 12-11= 1

n = number of digits between the term i.e. total digits between 11 to 60

Sn = sum of all the digits of the ap

Sn=n/2[2a+(n-1)d]

Sn=49/2[2×11+(49-1)1]

Sn=49/2[22+48×1]

Sn=49/2[22+48]

Sn=49/2×70

Sn=49×35

Sn=1715

hence sum of all numbers between 11 to 60 is 1715