If 70% of the members remembered the password but 21 members forgot, then how many members were there in all?
+26403 If 70% of the members remembered the password but 21 members forgot, then how many members were there in all?
m = members
p = 70 %
\(\small{ \begin{array}{rcl} m &=& m\cdot p + \underbrace{(1-p)\cdot m}_{=21} \\ m &=& m\cdot p + 21\\\\ m -m\cdot p &=& 21\\\\ m(1- p) &=& 21\\\\ m &=& \frac{ 21} { 1- p} \qquad | \qquad p = 70 \% \\\\ m &=& \frac{ 21} { 1- 70 \%} \\\\ m &=& \frac{ 21} { 100 \%- 70 \%} \\\\ m &=& \frac{ 21} { 30 \%}\\\\ m &=& \frac{ 21} { \frac{30}{100} } \\\\ m &=& \frac{ 21\cdot 100} { 30 } \\\\ m &=& \frac{ 2100 } { 30 } \\\\ m &=& \frac{ 210 } { 3 } \\\\ m &=& 70 \\ \end{array} }\)
There were 70 members in all
Let M be all members, then we have:
.70M + 21 =M
21=M - .70M
21=.30M divide both sides by .30
M=21/.30
M=70-number of all members
+26403 If 70% of the members remembered the password but 21 members forgot, then how many members were there in all?
m = members
p = 70 %
\(\small{ \begin{array}{rcl} m &=& m\cdot p + \underbrace{(1-p)\cdot m}_{=21} \\ m &=& m\cdot p + 21\\\\ m -m\cdot p &=& 21\\\\ m(1- p) &=& 21\\\\ m &=& \frac{ 21} { 1- p} \qquad | \qquad p = 70 \% \\\\ m &=& \frac{ 21} { 1- 70 \%} \\\\ m &=& \frac{ 21} { 100 \%- 70 \%} \\\\ m &=& \frac{ 21} { 30 \%}\\\\ m &=& \frac{ 21} { \frac{30}{100} } \\\\ m &=& \frac{ 21\cdot 100} { 30 } \\\\ m &=& \frac{ 2100 } { 30 } \\\\ m &=& \frac{ 210 } { 3 } \\\\ m &=& 70 \\ \end{array} }\)
There were 70 members in all
