A ratio can be written in three different ways: 3 to 4, 3:4, and 3/4
What does this mean? It means that for every group of 7 students (3+4) there are 3 boys and 4 girls. And how many groups do we have? We have:
245/7= 35 We have 35 groups, and we just said that each group has 3 boys and 4 girls:
35*3= 105 boys
35*4= 140 girls
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Let's say the APR is 5%. That means you get 5% of your balance back every year. The $100 balance would get $5 back, the $500 balance would get $25 back, and the $1000 balance would get $50 back. Therefore, all of the balances would take the same amount of time to double, and it would take all of them 20 years.
$5*20 years=$100
$25*20 years=$500
$50*20 years=$1000
Factor out cosx: cosx(sinx-2)=0
cosx=0 or sinx-2=0
cosx=0 or sinx=2
the largest value of sinx is 1, sinx will never be 2, so cosx=0, x=π/2 or 3π/2 are the two answers.
