It’s highly likely the spending rate is given on the test, but since you asked.
For foundations, if it’s not given and there are no clues in the question (unlikely), it’s most likely a private foundation that has a 5% spending rate. Add that (or multiply 1 + spending rate) to the management fees and inflation for spending rate.
If it’s an endowment, it’s extremely unlikely no information is given because there is no standard spending rate. The only other way this is given I would expect is for them to give a percentage funding rate.
Example: Big Return investments manages a $100 million endowment portfolio for Overpriced State University. The goal of the university is to support the university by paying 25% of operating expenses. Those expenses are expected to be $10 million this year. In this case, the real spending rate is 2.5% ($10 million X 25% is $2.5 million — $2.5 million/$100 million = 2.5%).
The only other way is if the endowment or foundation follows a spending rule. This should be disclosed in the question. The two main ones are:
Rolling three year average: (Ending balance t-1, Ending balance t-2, Ending balance t-3)/3 X Spending rate
Geometric average: Percentage Weight (usually given) X (last year’s spending figure) X (1 + Inflation) + (1- Percentage Rate) X Spending Rate X Ending Value t-1