Tim worker estimates his taxable income will be $7000. He is paid twice a month or 24 times a year. Because Tim has only one source of income, he uses the tax tables to estimate how much will be deducted from his pay for withholding

Ol' Tim will not be subject to income tax at that level. But he will pay social security, the rate is 7.65%. 
Time may be eligible for other credits such as the earned income, making work pay, credit credit, etc. 
We need a lot more info, but Tim should be withheld at this level.