def interpolatePercentCover(percentDatePrev, percentDateAfter, percentCoverPrev, percentCoverAfter, cutDate):
    """
    inputs: percentDatePrev - date obj - date prior to cut date that recorded the percent cover
            percentDateAfter - date obj - date after the cut date that recorded the percent cover
            percentCoverPrev - float - percent cover measured on percentDatePrev
            percentCoverAfter - float - percent cover measured on percentDateAfter
            cutDate - date obj - the date a variety was cut and its yield was measured.
    output: float between 0.0 and 1.0 representing the estimated percent cover on 
    """
    # find the amount days between the times the percent cover was measured
    daysBetweenCoverMeasurements = percentDateAfter - percentDatePrev
    
    # find the amount of days between the cut date and the date after it where the percent cover was measured
    daysBetweenCutDateAndCoverMeasurement = percentDateAfter - cutDate
    
    # get the ratio
    ratio = (1.0*daysBetweenCutDateAndCoverMeasurement)/(daysBetweenCoverMeasurements)
    
    # get the percent cover on the cutDate
    cutPercentCover = (-1.0)*(ratio*(percentCoverAfter - percentCoverPrev) - percentCoverAfter)
    
    # return result
    return cutPercentCover