A power distribution company bills six households — P, Q, R, S, T and U — for their electricity consumption every month. The table below shows the units of electricity consumed by each household in each of five months (January to May).
| Household | Jan | Feb | Mar | Apr | May |
|---|---|---|---|---|---|
| P | 120 | 150 | 180 | 140 | 160 |
| Q | 200 | 180 | 220 | 210 | 190 |
| R | 90 | 100 | 95 | 110 | 105 |
| S | 250 | 240 | 260 | 230 | 270 |
| T | 160 | 170 | 150 | 180 | 165 |
| U | 130 | 140 | 135 | 150 | 145 |
The monthly bill for a household is computed using a slab (tiered) tariff:
- For the first 100 units: ₹4 per unit
- For the next 100 units (i.e., units 101 to 200): ₹6 per unit
- For units beyond 200: ₹8 per unit
For example, a household consuming 250 units in a month is billed 100×4 + 100×6 + 50×8 = 400+600+400 = ₹1,400 for that month.
| Household | Jan | Feb | Mar | Apr | May |
|---|---|---|---|---|---|
| P | 120 | 150 | 180 | 140 | 160 |
| Q | 200 | 180 | 220 | 210 | 190 |
| R | 90 | 100 | 95 | 110 | 105 |
| S | 250 | 240 | 260 | 230 | 270 |
| T | 160 | 170 | 150 | 180 | 165 |
| U | 130 | 140 | 135 | 150 | 145 |
The monthly bill for a household is computed using a slab (tiered) tariff:
- For the first 100 units: ₹4 per unit
- For the next 100 units (i.e., units 101 to 200): ₹6 per unit
- For units beyond 200: ₹8 per unit
For example, a household consuming 250 units in a month is billed 100×4 + 100×6 + 50×8 = 400+600+400 = ₹1,400 for that month.
Question 1
Single correct option
Which household paid the highest total electricity bill over the five months (Jan–May combined)?
- A. Q
- B. S
- C. T
- D. P
Show answer and solution
Answer: (B) S
Compute each household's 5-month bill using the slab tariff. S consumes the most units every month (all above 200), so each month it is billed at all three slabs. S's monthly bills are ₹1,400, ₹1,320, ₹1,480, ₹1,240 and ₹1,560, totalling ₹7,000 — the highest among all households (Q totals ₹5,060, the next highest).
Question 2
Single correct option
In how many (household, month) instances did the monthly consumption exceed 200 units?
- A. 5
- B. 6
- C. 7
- D. 8
Show answer and solution
Answer: (C) 7
Scan the table for entries strictly greater than 200. Household Q exceeds 200 in March (220) and April (210) — 2 instances. Household S exceeds 200 in all five months (250, 240, 260, 230, 270) — 5 instances. No other household ever crosses 200. Total = 2 + 5 = 7 instances.
Question 3
Numerical answer
What was the total amount billed (in ₹) to all six households combined in the month of March?
Show answer and solution
Answer: 5210
March consumption: P=180 (bill=400+6×80=880), Q=220 (bill=400+600+8×20=1160), R=95 (bill=4×95=380), S=260 (bill=400+600+8×60=1480), T=150 (bill=400+6×50=700), U=135 (bill=400+6×35=610). Sum = 880+1160+380+1480+700+610 = 5,210.
Question 4
Numerical answer
For household S, what percentage (rounded to the nearest whole number) of its total five-month bill was billed in the month of May?
Show answer and solution
Answer: 22
S's monthly bills are ₹1,400, ₹1,320, ₹1,480, ₹1,240 and ₹1,560 (May), totalling ₹7,000. May's share = 1,560/7,000 × 100 ≈ 22.3%, which rounds to 22%.
Question 5
Single correct option
What is household Q's average billing rate across the five months, i.e., (total bill ÷ total units consumed), in ₹ per unit?
- A. ₹4.60
- B. ₹5.06
- C. ₹5.60
- D. ₹6.00
Show answer and solution
Answer: (B) ₹5.06
Q's monthly units are 200, 180, 220, 210, 190 (total 1,000 units), and its monthly bills are ₹1,000, ₹880, ₹1,160, ₹1,080, ₹940 (total ₹5,060). Average rate = 5,060/1,000 = ₹5.06 per unit — higher than ₹4 because slab pricing rises with usage.
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