QB_PH_GA_026: Analytical & Spatial Aptitude

A clock strikes once at 1 o'clock, twice at 2 o'clock, thrice at 3 o'clock, and so on. How many total strikes does the clock make in one complete 24-hour day?

Correct Answer

### Step-by-Step Derivation & Verification: 1. **Strikes in One 12-Hour Period**: $\sum_{k=1}^{12} k = \frac{12(12 + 1)}{2} = \frac{12 \times 13}{2} = 6 \times 13 = 78$ 2. **Full 24-Hour Day Operation**: A traditional analog striking clock repeats the 1-to-12 sequence twice in a 24-hour cycle: $\text{Total Strikes} = 2 \times 78 = 156$ 3. **Official Answer**: 156.