from typing import List
from typing import Tuple


def get_mean_gvi(gvi_exps: List[Tuple[float, float]]) -> float:
    """Returns mean GVI by the list of GVI + length pairs (tuples).
    """
    length = sum([length for _, length in gvi_exps])
    sum_gvi = sum([gvi * length for gvi, length in gvi_exps])
    return round(sum_gvi/length, 2)