A U. S. Senator from Indiana wanted to know what all her constituents thought about the Clean Air Act that was coming up for a vote in the Senate. She sent a letter to a sample of 257 Indiana voters asking them if they supported the Clean Air Act even if it meant they would have to pay higher prices for gasoline. The results indicated that 39% of the sample supported the Clean Air Act, even if it meant higher gasoline prices. The sample of Indiana voters was intended to represent all Indiana voters; therefore, the value of 39% would be called .