To find out how much Alvin's family will need to pay, we first need to calculate how much money Alvin will save over two years.
Alvin saves $250 a month for 24 months (2 years):
\[ \text{Total savings} = 250 \text{ dollars/month} \times 24 \text{ months} = 6,000 \text{ dollars} \]
Next, we will subtract his total savings from the cost of his training:
\[ \text{Cost of training} - \text{Total savings} = 9,500 \text{ dollars} - 6,000 \text{ dollars} = 3,500 \text{ dollars} \]
Therefore, his family will need to pay $3,500.