Identify which of the following costs are relevant to the decisions specified:

(a) The salary to be paid to a market researcher who will oversee the development of a new product. This is a new post to be created especially for the new product but the $\$ 12,000$ salary will be a fixed cost.

Is this cost relevant to the decision to proceed with the development of the product?

(b) The $\$ 2,500$ additional monthly running costs of a new machine to be purchased to manufacture an established product. Since the new machine will save on labour time, the fixed overhead to be absorbed by the product will reduce by $\$ 100$ per month.
Are these costs relevant to the decision to purchase the new machine?

(c) Office cleaning expenses of $\$ 125$ for next month. The office is cleaned by contractors and the contract can be cancelled by giving one month's notice.
Is this cost relevant to a decision to close the office?

(d) Expenses of $\$ 75$ paid to the marketing manager. This was to reimburse the manager for the cost of travelling to meet a client with whom the company is currently negotiating a major contract. Is this cost relevant to the decision to continue negotiations?