Can anyone help with these questions?

The probability of producing a normal child by two parents who are carriers for an autosomal recessive disorder is

Guinea pig coat color is determined by a single gene. the allele for black coat color is dominant to brown. in a cross between twoblack-haired guinea pigs, 20 offspring are born. if both parents were heterozygous, probability would predict that approximately howmany of the 20 offspring would have brown hair?

What is the difference between a meteoroid and a meteor?