Check the picture below.
you can pretty much count those lengths off the grid.
recall that A = 1/2 bh.
Answer:
27.5 minutes
Step-by-step explanation:
Using,
R/R' = 2ᵃ/ᵇ------------------ Equation 1
From the equation,
R = mass of Element X before radioactive decay, R' = mass of element X after radioactive decay, a = Time taken, b = half life.
Given: R = 870 grams, R' = 154 grams, b = 11 minutes.
Substitute these values into equation 1
870/154 = 2ᵃ/¹¹
(870/154)¹¹ = 2ᵃ
Solve for a
2ᵃ = (5.649)¹¹
2ᵃ = 187061.26
Taking the logarithm of both side,
Log2ᵃ = Log(187061.26)
⇒ a = log(187061.26)/log2
a = 8.272/0.301
a = 27.5 minutes
e follSOLUTION
Given the question in the image, the following are the solution steps to answer the question
STEP 1: Write the general equation of an ellipse

STEP 2: Identify the parameters
the length of the major axis is 2a
the length of the minor axis is 2b

STEP 3: Get the equation of the ellipse

STEP 4: Pick the nearest equation from the options,
Hence, the equation of the ellipse in the image is given as:

OPTION A
135
cross multiply 9*20 then divide by 8