A lot farther than most people would think!
Watch the short video.
"So how far away would a tennis ball Moon have to be from the basketball Earth to be to scale? On average the moon is 380,000 km (235,000 miles) from the Earth, a distance of about 110 times its own diameter. A tennis ball would then have to be 110 x 6.7 cm = 7.37 meters (about 24 feet) from the basketball. That's a lot farther than most people would think!"