Strontium 90 is a radioactive isotope that decays according to the eqaution A t = A 0 e − 0.0244 t , where A 0 is the initial amount present and A t is the amount present after t years. If you begin with 400 grams of strontium 90,
(a) How much strontium 90 will be left after 10 years? Round your answer to the nearest tenth of a gram. grams
(b) When will 105 grams of strontium 90 be left? Round your answer to the nearest tenth of a year. years
HELP

Step-by-step explanation:

t = A 0 e − 0.0244 t  

t=10   yrs

Ao=400  gm

At=  400 e^-.0244(10) = 313.4 gm

At = 105 = 400e^-.0244t    solve for t

    105/400 = e^-.0244t

ln (105/400) = -.0244 t

t = 54.8 years

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.

he has now walked a total of what?

if i know what this is maybe i can

step-by-step explanation: