(i) For the electricity rate, the cost upto 50 units is Rs. 500 and the rate of extra unit is Rs. 15 for a room rental. (a) How many electricity is consumed for 1 unit? (b) How many additional units did the tenant consume if their monthly bill was Rs. 621.50 ? (c) Calculate the bill for the next month if the tenant uses 105 units of electricity. (d) Compare the bills for two successive months'.

Let's break down the problem step by step. ### Known Conditions: 1. Cost for the first 50 units: Rs. 500 2. Rate for additional units beyond 50: Rs. 15 per unit 3. Monthly bill for the tenant: Rs. 621.50 ### Step (a): How many electricity is consumed for 1 unit? To find the cost per unit for the first 50 units, we can calculate: \[ \text{Cost per unit for first 50 units} = \frac{\text{Total cost for 50 units}}{\text{Number of units}} = \frac{500}{50} = 10 \] So, the cost for 1 unit for the first 50 units is Rs. 10. ### Step (b): How many additional units did the tenant consume if their monthly bill was Rs. 621.50? First, we need to determine how much of the bill is attributed to the first 50 units: \[ \text{Cost for first 50 units} = 500 \] Now, we can find the remaining amount that corresponds to the additional units: \[ \text{Additional cost} = \text{Total bill} - \text{Cost for first 50 units} = 621.50 - 500 = 121.50 \] Next, we can find the number of additional units consumed: \[ \text{Number of additional units} = \frac{\text{Additional cost}}{\text{Rate for additional units}} = \frac{121.50}{15} = 8.1 \] Since the number of units must be a whole number, we round down to 8 additional units. ### Step (c): Calculate the bill for the next month if the tenant uses 105 units of electricity. For 105 units, the first 50 units cost Rs. 500. The additional units are: \[ \text{Additional units} = 105 - 50 = 55 \] Now, we calculate the cost for these additional units: \[ \text{Cost for additional units} = 55 \times 15 = 825 \] Now, we can find the total bill for the next month: \[ \text{Total bill} = \text{Cost for first 50 units} + \text{Cost for additional units} = 500 + 825 = 1325 \] ### Step (d): Compare the bills for two successive months. - First month bill: Rs. 621.50 - Second month bill: Rs. 1325 Now, we can compare the two bills: \[ \text{Difference} = \text{Second month bill} - \text{First month bill} = 1325 - 621.50 = 703.50 \] ### Summary of Results: - (a) Cost for 1 unit for the first 50 units: Rs. 10 - (b) Additional units consumed: 8 units - (c) Bill for the next month (105 units): Rs. 1325 - (d) Difference between the two bills: Rs. 703.50 If you have any further questions or need additional calculations, feel free to ask!