Answer:
4.2
Step-by-step explanation:
The "allowance" is the difference between the maximum shaft size and the minimum hole size.
maximum shaft = C +D = 8.5 +0.1 = 8.6
minimum hole = A -B = 4.8 -0.4 = 4.4
Allowance = 8.6 -4.4 = 4.2
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For an interference fit, the allowance is negative.