This question tests about inverse proportions. The formula x = k / y is given in the notebook, where k is the constant. You should have solved (i) using the mentioned formula, where you acquire the value of constant k.
(ii) gives the time required, which is 10 hours. With two known variables, you are able to solve for the amount of mechanics required.
The number of mechanics must be rounded up, because humans must exist in whole numbers, and any number lower than 34 will have a time taken longer than 10 hours. Therefore, the answer is 34.

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