Question 222201
I can solve (4)
Let {{{x}}} = liters of the 10% solution needed
given:
silver Iodide in 4% solution = {{{.04*7 = .28}}} liters
Silver Iodide in 10% solution = {{{.1x}}}
{{{(.28 + .1x)/(7 + x) = .06}}}
{{{.28 + .1x = .06*(7 + x)}}}
{{{.28 + .1x = .42 + .06x}}}
{{{.04x = .14}}}
{{{x = 3.5}}}
3.5 liters of the 10% solution are needed
check:
{{{(.28 + .1x)/(7 + x) = .06}}}
{{{(.28 + .1*3.5)/(7 + 3.5) = .06}}}
{{{(.28 + .35)/ 10.5 = .06}}}
{{{.63/10.5 = .06}}}
{{{.63 = .06*10.5}}}
{{{.63 = .63}}}
OK