Challenge: Suppose you know the initial dose of a drug is 500mg, and 3 hours later, there's 325mg left, but you don't kn

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Challenge Suppose You Know The Initial Dose Of A Drug Is 500mg And 3 Hours Later There S 325mg Left But You Don T Kn 1 (131.16 KiB) Viewed 47 times

Challenge: Suppose you know the initial dose of a drug is 500mg, and 3 hours later, there's 325mg left, but you don't know the base multiplier (b). Use this information in the equation y=a⋅bx to solve for b. y=a⋅bx First substitute in a=500, and use x=3 with y=325. The equation will look like: Now solve for b : first divide both sides by 500 , and you get: =b3 The next challenge is how to undo a third power--"uncube it." If your calculator has a cube root (look for 3…​−-it may be under the MATH menu) you can use it to undo the third power: 30.65​=3b3​ =b If your calculator doesn't have that key, you can undo the third power by raising both sides of the equation to a 31​ power: (0.65)(31​)=(b3)(31​) make sure that the 31​ is entered in parentheses (1/3) and you should get: 0.866239…=b So that the equation for this problem is y=500(0.866)x