The 7th grade class experienced a 15% decrease in enrollment. last year, the 7th grade class had 280 students. how many students are enrolled in the 7th grade class this year?

238 students are enrolled in the 7th grade class this year

Solution:  

Given that

Percentage decrease in number of students enrolled in 7th grade = 15%

Number of students enrolled last year = 280  

Need to determine number of students enrolled in 7th grade this year.

Lets assume number of students enrolled this year = x  

Percentage decrease in enrollment = (Number of student enrolled last year – Number of students enrolled this year) whole divided by number of students enrolled last year multiplied by 100

Hence number of students enrolled this year = 238.

the answer is; biodiversity resulting from few ancestors

adaptive radiation occurs when a population is subjected to a large natural environment with spatial ecological variations. the parts of the population in the different ecologies begin to adapt to their local environments. due to non-random mating across the large populations, this causes the different populations from the large population to speciate within their local environments. they, therefore, diverge to different species sharing a common ancestor.