How Many Bank Accounts Have Deposits Below $1500?

[safina]

Homework Statement

In a certain bank, there 10,000 deposit accounts. A simple random sample of 36 accounts was drawn without replacement. If Y denotes the amount (in units of 100) in a deposit account, the following data were obtained from the sample: \sum^{n}_{i=1}y_{i}= 900 and \sum^{n}_{i=1}y^{2}_{i}= 25,335.
Suppose of 36 accounts drawn in the sample, 12 had a deposit less than 15 (in units of 100). Estimate the total number of accounts having a deposit of less than 15 and its standard error.

I were not able to attempt a solution since I am confused if 12 is already the total number of accounts having a deposit of less than 15. Could someone help me understand this problem and guide me here?

 

[CompuChip]

They mean: out of the 36 in the sample, there were 12 with a deposit less than 15.
How many accounts with less than 15 do you expect in the total of 10,000 accounts?