I need a formula that will reference column A when column B has reached/eclipsed a given number.

Example: When column B range reaches or surpasses "30.00", tell me the corresponding value in column A

The expected, and correct, result of the formula should be "4"

Data
Column A - Column B
1 - 25.05
2 - 27.64481038
3 - 29.99606543
4 - 32.1630163
5 - 34.18397103
6 - 36.08544701
7 - 37.88672718
8 - 39.60236759
9 - 41.2436836
10 - 42.8196825

I need a formula that will reference column A when column B has reached/eclipsed a given number.

Example: When column B range reaches or surpasses "30.00", tell me the corresponding value in column A

The expected, and correct, result of the formula should be "4"

Thanks