Magnetism: magnetic feild strength of a wire

[physicsStudent00]

Homework Statement

A wire 1.0 mm in diameter carries 5.0 A distributed uniformly over its cross section.

a) Find the field strength 0.10 mm from its axis.

b) Find the field strength at the wire’s surface

Homework Equations

The Attempt at a Solution

I've used the Biot-Savart Law for a wire for both of the questions and had the wrong answer both times. Using the wire law: B=(μ_0)(I)/2πr
a) B=(μ_0)(5)/2π((1+0.1)*10^-3) = 9.091*10^-4
b) uses the same approach

i don't understand what numbers to be using or if I'm using the wrong equation's here?
any help is much appreciated

 

[BvU]

a) asks for 0.1 mm from its axis, not from its surface

 

[physicsStudent00]

a) asks for 0.1 mm from its axis, not from its surface

by taking the radius as 0.1*10^-3 it gives 0.01T which still is wrong

 

[BvU]

How much current is within this $10^{-4}$ m radius ?

In other words: does your

Using the wire law: B=(μ_0)(I)/2πr

apply inside the wire ?