A clock strikes once at 1 o'clock, twice at 2 o'clock , thrice at 3 o'clock and so on. How many times will it strikes in 24 hours?
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Answer:
156 times.
Step-by-step explanation:
We know sum of n terms in Arithmetic Progression series is
Sn = n÷2{2a+(n-1)r}, where n is the number of terms, a is the first term, r is the difference that is added to next every term. i.e. r is the common difference between two successive terms. Here a=1, r=1, n=12.
In first 12 hour clock strikes the amount Sn=12÷2{2×1+(12-1)×1}=78 times. In 24 hours clock strikes 2×Sn=156 times.
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