Purple flowers are dominate over white flowers. a heterozygous purple flower is crossed with another heterozygous purple flower. the ratio of purple flower to white would be

3:1

because if you make a table you see that three boxes have an uppercase while only one has the lowercase letter making it 3:1

   3:1

Explanation:

According to Mendel’s law of inheritance, in a monohybrid cross, dominant allele appears phenotypically in the F1 generation and on crossing between F1 hybrids, the ratio of dominant to recessive will be 3:1. Thus in the given question when the dominant purple flower is crossed with recessive white flower, the ratio of purple flower to white would be 3:1.  

the answer to you question is   jet streams

ya the other dude is right