[問題]GWD-11-19

[游客]

Q19

In a certain region, the number of children who have been vaccinated against rubella is twice the number who have been vaccinated against mumps. The number who have been vaccinated against both is twice the number who have been vaccinated only against mumps. If 5,000 have been vaccinated against both, how many have been vaccinated only against rubella?

25,00; 7,500; 10,000; 15,000: 17,500

霧煞煞

[homaru]

打r疫苗的人數是打m疫苗人數的兩倍
兩種都打的人數是只打m的兩倍
只打m的人數=打m的-兩種都打的
r=2m
both=2*(m-both)-->5000=2*(m-5000)-->m=7500
只打r的=打r的-兩種都打的=r-both=2m-both=2*7500-5000=10000
C

[agk99]

劃個范式圖就行

[游客]

了.....