19 of the guests at a safari park were boys. 80% of the remaining guests were girls and the rest were adults. The total number of boys and adults is 171 less than the number of girls. After some girls entered the safari park, 80% of the guests that remained were girls. How many girls entered the safari park?
Boys |
Adults |
Girls |
Total |
1x5 |
8x5 |
9x5 |
|
1x8 |
4x8 |
|
5 |
8 |
32 |
45 |
|
Boys and adults |
Girls |
Before |
13x1 = 13 u |
32x1 = 32 u |
Change |
|
+ 20 u |
After
|
1x13 = 13 u |
4x13 = 52 u |
80% =
80100 =
45 Adults : Girls = 1 : 4
The total number of adults and girls at first is repeated. Make the total number of adults at first the same. LCM of 8 and 5 is 40.
80% =
80100 =
45 When some girls entered, the total number of boys and adults remains unchanged. Make the total number of boys and adults the same. LCM of 13 and 1 is 13.
The total number of boys and adults is 171 less than the number of girls.
Number of less boys and adults than the number of girls at first
= 32 u - 13 u
= 19 u
19 u = 171
1 u = 171 ÷ 19 = 9
Number of girls who entered the safari park
= 52 u - 32 u
= 20 u
= 20 x 9
= 180
Answer(s): 180