Answer:
Step-by-step explanation:
The water district has been charging its customers a flat rate of $3.25 per HCF. If a family uses an average of 56 HCF per month, the total charge would be
3.25 × 56 = $182
Because of a drought emergency, it is instituting a block rate of $3.60 for the first 20 HCF and $4.85 for the next 40 HCF. If a family uses an average of 56 HCF per month, the total charge would be
(3.6 × 20) + 4.85(56 - 20)
= 72 + 174.6
= $246.6
The increase in the charge is
246.6 - 182 = $64.6
The percent by which their average bill increased under the block system is
64.6/182 × 100 = 35.5%