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3 years ago

The ratio of girls to boys in French class is 5:4. There are 12 boys in the class. How many girls are there?

Mathematics

2 answers:

jolli1 [7]3 years ago

8 0

Answer:

Step-by-step explanation:

5/4=15/12

Svet_ta [14]3 years ago

7 0

Answer:

15 girls

Step-by-step explanation:

G : B : total

5 : 4 : 9

? :12: ?

No. of girls = (12x5)/4 = 15 girls

we put the ratio between girls and boys then we add the (total) or(sum) beside them in the same ratio then the summation of the ratio, like (5 +4 = 9) and then under the word "boys" we put the number given in the question which is (12) , now we need to know the number of girls in the class so we use the cross multiplication which i wrote at first.

by that, you can calculate no. of girls and no. of students in the whole class if you want.

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3 years ago

Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

Aleonysh [2.5K]

Answer:

t=5.18 minute

Step-by-step explanation:

Using Newton's law of cooling

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$\frac{dT}{dt}=-k(T-T_{s})\\\frac{dT}{(T-T_{s})}=-k*dt\\\int\limits {\frac{1}{T-T_{s} } } \, dT=-\int\limits {k} \, dt\\ln(T-T_{s})=k*t+C\\e*ln(T-T_{s})=e^{k*t+C} \\T-T_{s}=e^{k*t}*e^{C}\\e^{C}=C\\T-T_{s}=e^{k*t}*C\\T=T_{s}+e^{k*t}*C$

To find constant knowing the time and the temperature the first step of the change of energy in cup of coffee

$T=T_{s} +e^{-k*t}*C\\ C=190-66=124\\170=66+124*e^{-k*2}\\ 170-66=124*e^{-k*2}\\ln(\frac{104}{124})=ln*e^{-k*2}\\-0.175=-k*2\\k=0.08794$

Now using the constant of decreasing can find the time to be a 145 temperature the cup of coffee

$145=66+124*e^{-k*t} \\145-66=124*^{-0.087*t}$

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3 years ago

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Answer:

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Step-by-step explanation:

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The ratio of girls to boys in French class is 5:4. There are 12 boys in the class. How many girls are there?​

The ratio of girls to boys in French class is 5:4. There are 12 boys in the class. How many girls are there?