We know that 90% is equivalent to 315 people and we want to know how many people are equivalent to 100%. So, using the rule of three, we get:
90% ------------------- 315
100% ------------------ X
Where X is the number of people surveyed.
Solving for X, we get:
![X=(100\cdot315)/(90)=350](https://img.qammunity.org/2023/formulas/mathematics/college/4kagffbj0u8vc0xws7xzpwiohg05mb6vmk.png)
Therefore, 350 people were surveyed.
Answer: 350 people