Answer to this questions Please *Question 8*
A clock strikes once at 1 o’clock (am or pm), twice at 2 o’clock (am or pm), thrice at 3 o’clock (am or pm) and so on. How many times will it strike in 24 hours?
Select one:
1. 78
2. 136
3. 156
4. 196
1+2+3+...+n = n(n+1)/2
so, from 1:00 to 12:00 it strikes 12*13/2 = 78 times
and it does that twice in 24 hours.
156
To find the answer to this question, we need to determine how many times the clock strikes in a 24-hour period. Notice that the clock strikes once at 1 o'clock, twice at 2 o'clock, three times at 3 o'clock, and so on.
We can see a pattern here. The clock strikes n times at n o'clock. Therefore, to find out how many times the clock strikes in a 24-hour period, we need to calculate the sum of the strikes from 1 to 12 (as 12 o'clock is the last hour of this period).
To calculate this sum, we can use the arithmetic series formula:
Sum = (n/2)(first term + last term),
where n is the total number of terms.
In this case, n = 12, the first term is 1, and the last term is 12. Plugging these values into the formula:
Sum = (12/2)(1 + 12)
= 6(13)
= 78
So, the clock will strike 78 times in a 24-hour period.
The correct answer is option 1: 78.