The electricity bill of a certain establishment is partly fixed and partly varies as the number of units of electricity consumed. When in a certain month 540 units are consumed, the bill is Rs. 1800. In another month 620 units are consumed and the bill is Rs. 2040. In yet another month 500 units are consumed. The bill for that month would be:
1. Rs. 1605
2. Rs. 1680
3. Rs. 1840
4. Rs. 2050

• Here
  we can find fixed unit by taking their HCF
  so HCF of 540,620 and 500 is 40
  so fixed unit is 40
  
  now suppose price of variable unit is x and fixed unit is y
  
  500x+40y=1800 --------->(1)
  
  580x+40y=2040 --------->(2)
  
  after solving condition 1 and 2
  we gate x=3 and y=30/4
  in 500 unit 40 fix and 460 varies
  40*(30/4)+460*3=1680 ---->ANS
  
• 10 years agoHelpfull: Yes(11) No(3)
• let fix unit be x and cost of each unit be y
  540y + x =1800 (1)
  620y + x = 2040 (2)
  solving both the equation we will have y=3
  now placing y value in any of the equation give x=180(fixed value)
  so now we will have 180 +(500*3)=1680
  so b is correct option
  
• 10 years agoHelpfull: Yes(7) No(1)
• 2. Rs. 1680
• 10 years agoHelpfull: Yes(4) No(3)
• dont know math baby hcf is 20
• 4 years agoHelpfull: Yes(0) No(1)