Airtel, a GSM service provider, offers a post-paid plan called Airtel One for its customers, with the tariff details shown below. Mohan made an STD call, within 100 km, for 30 minutes and spent 100 minutes on local calls, split 30% on landline, 40% on GSM and 30% on Airtel. Rohan made an STD call, within 150 km, for 18 minutes and spent 120 minutes on local calls, split 30% on GSM, 40% on landline and 30% on Airtel. Who spent more on calls that month?
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Work out each person's local call cost first using the tariff table, then add the STD leg using the rate band that fits their distance.
Step 1: Read the local call rates from the table. Airtel local calls cost Rs. 1 per minute, GSM local calls cost Rs. 1 per minute, and Landline local calls cost Rs. 2 per minute.
Step 2: Read the matching STD band. The 50 to 200 km row covers both Mohan's 100 km call and Rohan's 150 km call. This row charges Rs. 1.50 per minute for Airtel and GSM, but Rs. 2 per minute for Landline. Since we are not told which network carried each STD call, we check both possible rates.
Step 3: Work out Mohan's local bill. 30% of 100 minutes is 30 minutes on landline, costing \( 30 \times 2 = 60 \). 40% of 100 minutes is 40 minutes on GSM, costing \( 40 \times 1 = 40 \). 30% of 100 minutes is 30 minutes on Airtel, costing \( 30 \times 1 = 30 \). Adding these gives Rs. 130 in local charges.
Step 4: Add Mohan's STD charge. 30 minutes at Rs. 1.50 gives Rs. 45, or 30 minutes at Rs. 2 gives Rs. 60. So Mohan's total is either \( 130+45=175 \) or \( 130+60=190 \).
Step 5: Work out Rohan's local bill. 30% of 120 minutes is 36 minutes on GSM, costing \( 36 \times 1 = 36 \). 40% of 120 minutes is 48 minutes on landline, costing \( 48 \times 2 = 96 \). 30% of 120 minutes is 36 minutes on Airtel, costing \( 36 \times 1 = 36 \). Adding these gives Rs. 168 in local charges.
Step 6: Add Rohan's STD charge. 18 minutes at Rs. 1.50 gives Rs. 27, or 18 minutes at Rs. 2 gives Rs. 36. So Rohan's total is either \( 168+27=195 \) or \( 168+36=201 \).
Final Answer: Mohan's highest possible bill is Rs. 190, and Rohan's lowest possible bill is Rs. 195, so Rohan spends more no matter which STD rate applies. \[ \boxed{\text{Rohan spent more}} \]
