The key insight here is to notice that when 20% of the flashes are removed, 80% remain. Call
the number of flashes on the first day F. Then the number of flashes on the second day is. On the third day, the number is 80% or of of F—which you can express
more simply as . Similarly, on the fourth day, the number of flashes is .
You’re given that the number of flashes on the fourth day is 704, so
If , then . Use your calculator: F = 1,375.6 . D
When you’re given two parts of a three-part formula, determining the third part is almost
always a smart move. Begin withThenand least + a + b + c + d + greatest = 18. If the average of least and greatest is 5, then least +
greatest = 10, so 10 + a + b + c + d = 18 and a + b + c + d = 8. Only in (D) do the numbers not
sum to 8.7 . C
An intended part of the challenge of this question is the quantity and complexity of the data
it puts in front of you. Organize and relate these data by placing them in a structure such as
this one:
rate × time = distance
Leg 1 _____ _____ _______
Leg 2 _____ _____ _______Call the rate of Leg 1 r and the time of Leg 1 t. Then,