A pharmacist has two vitamin-supplement powders. The first powder is 10% vitamin B1 and 30% vitamin B2. The second is 15% vitamin B1 and 20% vitamin B2. How many milligrams of each powder should the pharmacist use to make a mixture that contains 80 mg of vitamin B1 and 200 mg of vitamin B2?

mg of powder 1 and mg of powder 2

Explanation:

Let "X" denotes weight of powder 1 added to the new mixture and  "Y" denotes weight of powder 2 added to the new mixture

Total weight of vitamin B1 in the mixture is equal to mg

Total weight of vitamin B2 in the mixture is equal to mg

Equation 1

Equation 2

Let us simplify the above two equations, we will get

Substituting value of X in equation 2 we get

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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