ratios

[cosmic pivot]

Help

[verbal meadow]

,rotate

[charred kindle]

you can do the tree thing

probability tree

[jolly dove]

fraction of ppl who passed = fraction of children who passed + fraction of adults who passed

fraction of children who passed = fraction of children to adults * fraction of children who passed to failed

= 3/8 * 4/5 = 3/10

fraction of adult who passed = fraction of adult to children * fraction of adults who passed to failed

= 5/8 * 7/9 = 35/72

fraction of ppl who passed = fraction of children who passed + fraction of adults who passed

= 35/72 + 3/10 = 175/360 + 108/360 = 283/360