Math, asked by vtarun9603, 3 months ago

one man started a work on first day, the second day one more joined with him the next day one more joined everyday one new person joined until work get completed. if the work is completed in 15 days how many days it takes for 10 men to complete the same work if they joined regularly?​

Answers

Answered by roshanmahudeeswaran
2

Answer:

7 and 1/2 day

Step-by-step explanation:

1+2+3+....+N = 15

formula :

Sn= n/2 { 2a + (n-1)d }

15 = N/2 {2+N-1}

15 = N/2 {N+1}

30 = N ( N+1 )

30 = 5 ( 5+1 )

30 = 30

Here by N = 5

5 persons can do the work in 15 days,

10 persons can do the work in 15/2 = 7 1/2 days.

Answered by sweetyjindal1996sj
1

Step-by-step explanation:

on first day number of men = 1

work completed = 1

on second day number of men = 2

work completed = 2

on third day number of men = 3

work completed = 3

total work in 15 days = Sn = n/2 {2a+(n-1)d}

a = 1 = work on first day

Sn = 15 = total days

d = 1 = difference in every succeeding day's work

15= n/2 {2(1) +(n-1)1}

30 = n {2+n-1}

30 = n ( 1+n )

let the value of n be 5 so that his equation satisfied on both sides

30 = 5 (1 + 5)

30 = 5× 6

30 = 30

n= 5 work completed in 15 days

if n = 10 then work completed will be 15/2 = 7.5 days

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