Tt is found that an average volume of 24.25 ml of approximately 0.1 M NaOH is required to reach an endpoint in a titration with 25.00ml of 0.09917 M HCl solution. What is the NaOH concentration? Make sure to give answer to four significant figures.

What in the world is Tt.That may be "It is found that....".

mL HCl x M HCl = mL NaOH x M HCl

To find the concentration of NaOH, we can use the equation: M1V1 = M2V2

Where:
M1 = concentration of NaOH
V1 = volume of NaOH used (in liters)
M2 = concentration of HCl (given as 0.09917 M)
V2 = volume of HCl used (given as 25.00 ml, so we need to convert it to liters)

Let's start by converting the given volume of HCl to liters:
V2 = 25.00 ml = 25.00 ml / 1000 = 0.02500 L

Now, we can plug the values into the equation and solve for M1:
M1 * V1 = M2 * V2

M1 * 24.25 ml = 0.09917 M * 0.02500 L

Divide both sides by 24.25 ml:
M1 = (0.09917 M * 0.02500 L) / 24.25 ml

Evaluate the right side of the equation:
M1 ≈ 0.000100827 M

Now, let's round the answer to four significant figures:
M1 ≈ 0.0001008 M

Therefore, the concentration of NaOH is approximately 0.0001008 M.