She is correct because a negative subtracted by a negative is positive.
Answer:
16.7%.
Step-by-step explanation:
There are initially
pencils in the bag.
Take a pencil out of this bag of 47 pencils. 15 out of the 47 pencils blue. Let
represent the event of getting a blue pencil on the first pick. The probability of getting a blue pencil is:
.
There are now
pencils left in the bag. However, given that the first pencil removed from the bag is blue, the number of red pencils in the bag will still be 24. Take another pencil out of this bag of 46 pencils. Let
represent the event of getting a red pencil on the second pick. The possibility that the second pencil is red given that the first pencil is blue will be:
.
The question is asking for the possibility that the first pencil is blue and the second pencil is red. That is:
.
Answer:
1360 cm2
Step-by-step explanation:
It is still a rectangle, just slanted. So straiten it out a solve it like a normal area problem:
34 x 40 = 1360 cm2
The formula for half-life is:

A is the amount remaining, P is the initial amount, t is the time that has passed, and h is the half-life of the substance. Plug in the values that you know and solve:

Rounded to the nearest whole number, the density of the substance was about 13<span>mg / cm².</span>