A plant with genotype SsYy is crossed with a plant with genotype SsYy. What is the probability that the offspring of these plants will have smooth, yellow seeds?

62.5%

Explanation:

I posted a picture of the dihybrid cross I used to solve this below.  

Both smooth seeds and yellow seeds are dominant, so any genotype with a S and a Y would have smooth, yellow seeds.  10 out of 16 on the dihybrid cross had a S and Y.   can be simplified to .  

To find the percentage, divide 5÷8=0.625.  Multiply 0.625×100=62.5%

This means 62.5% of the offspring will have smooth yellow seeds.

the real answer is b. scintillation counter

this is a good question! i'll do some research and come back when i have the answer!