How do i know if this is true

Male koalas bellow during the breeding season, but do females pay attention? In the le 'KoalaElellowscsi-f are data on the responses of estrous female koalas to playbacks of bellows that had been modied on the computer to simulate male callers of different body size. Females were placed one at a time into an enclosure wi'd': loudspeakers playing bellows simulating a larger male on one side [chosen randomly} and a smaller male on the other side. Male bellows were played repeatedly, alternating between sides, over it] minutes. Females often tumed to look in the direction of a loudspeaker {invisible to her} during a trial. The data in rl'ioalaEiellowscsy' measure the preference of each of 15 females for the simulated sound of die 'largerl male. Preference was calculated as the number of looks toward the larger male minus the number of looks toward the smaller male. Preference is positive if a female looked more often toward the larger male, and is negative if the she looked more often to the small male. Based on this information, can we reject the null hypothesis that the mean of this 1trarlable is equal to an expected null value of zero? Answer TRUE for 'yes' and FALSE for 'no'. @I Tme O False \f