Dimples and long eyelashes are both autosomal dominant traits. If a woman with no dimples, who is heterozygous for long eyelashes, mates with a man who is heterozygous for dimples, and has short eyelashes, What are the chances that this couple produces a child who is heterozygous in EITHER trait?

Let the dominant allele for dimples be represented as "D" and the recessive allele be represented as "d".
Let the dominant allele for long eyelashes be represented as "L" and the recessive allele be represented as "l".
As per the question, the woman has no dimples and is heterozygous for long eyelashes, so her genotype would be: ddLl.
The gametes produced by the woman would be: dL and dl.
The man is heterozygous for dimples and has short eyelashes, so his genotype would be: Ddll.
The gametes produced by the man would be: Dl and dl.
Mating them we get the following offspring,

dL dl

Dl DdLl Ddll

Phenotype Dimples, Long eyelashes Dimples, short eyelashes

dl ddLl ddll

Phenotype No dimples, long eyelashes No dimples, short eyelashes

The genotype and the phenotype of the offspring obtained by the above cross is mentioned above.
The question demands to determine the chance that a child who is heterozyous for either trait is produced. This means the probability of the child who is hetrozygous for either the dimple trait or long eyelashes trait is to be found.
The genotypes of the offspring having either of the traits in heterozygous condition are, DdLl, Ddll and ddLl, respectively.
Three out of four possible offspring have the possibility of being heterozygous in either trait.
Hence, the probability of producing an offspring who is heterozygous in either trait is [tex]=\frac{3}{4} \times 100 = 75[/tex]%.