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Nishu Priya
CAT Preparation Community 9y ago
if a clock strikes once at 12 A.M. , twice at 1 A.M. , thrice at 2 A.M. and so on.How many times will the clock be struck in the course of 3 days? 1. 756. 2. 828. 3. 678. 4.1288
5
Akhil Tanakala 7y ago
At 12AM Clock strikes once = 1
At 1AM Clock strikes twice= 2
At 2AM Clock strikes thrice=3
.
.
.
.
At 11PM Clock strikes =23
After 3 days i.e. 72 hrs it'll strike 3(1+2+3+....+23) times.
So, the clock will strike= 3(1+2+3+....+23)
=n(n+1)/2
=3x24(23)/2
=23x12x3
=828
tejash raj 6y ago
At 11 pm clock strikes =24 times
Parth Savla 5y ago
At 11pm 24 why 23
Kritika Mer 5y ago
Sum of the series = n(n+1)/2
Series are as 1+2+3+....23 and here n= 23
So , putting value in the formula n(n+1)/2 , we get 23(24+1)/2 = 276
For 3 days, it will be 276 × 3 = 828 times.
Shagun Joshi 5y ago
The answer is 900 the above solution has been copied from Arun sharma's answers which is wrong for this particular question
