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3 years ago

-4f - 9 f + 15

Mathematics

1 answer:

Vikentia [17]3 years ago

8 0

Answer:

13f+15

Step-by-step explanation:

- plus - equals addition so you add 4 and 9 then the two - will equal to a + so there will be no sign there 15 cant be added to 13F because it doesnt have the same letter (f) (i said it in the simplest way possible hope u get a c or b ^^)

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There are 380 female students in a class. Male students make up 60% of the class. What is the total number of students in the cl

Ber [7]

Answer:

Step-by-step explanation:

If the males make up 60% of the class then

The females make up 100 - 60 = 40% of the class.

Females = 40% * x where x = the class size.

380 = 40/100 * x

380*100 =38000

38000 = 40 x

38000/40 = x

x =950

8 0

2 years ago

73 7/10−25 5/8<br><br><br>Enter your answer as a mixed number in simplest form.

VladimirAG [237]

Answer:

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Step-by-step explanation:

7 0

3 years ago

At 2 PM, a thermometer reading 80°F is taken outside where the air temperature is 20°F. At 2:03 PM, the temperature reading yiel

Alexeev081 [22]

Use Law of Cooling:
$T(t) = (T_0 - T_A)e^{-kt} +T_A$
T0 = initial temperature, TA = ambient or final temperature

First solve for k using given info, T(3) = 42
$42 = (80-20)e^{-3k} +20 \\ \\ e^{-3k} = \frac{22}{60}=\frac{11}{30} \\ \\ k = -\frac{1}{3} ln (\frac{11}{30})$

Substituting k back into cooling equation gives:
$T(t) = 60(\frac{11}{30})^{t/3} + 20$

At some time "t", it is brought back inside at temperature "x".
We know that temperature goes back up to 71 at 2:10 so the time it is inside is 10-t, where t is time that it had been outside.
The new cooling equation for when its back inside is:
$T(t) = (x-80)(\frac{11}{30})^{t/3} + 80 \\ \\ 71 = (x-80)(\frac{11}{30})^{\frac{10-t}{3}} + 80$
Solve for x:
$x = -9(\frac{11}{30})^{\frac{t-10}{3}} + 80$
Sub back into original cooling equation, x = T(t)
$-9(\frac{11}{30})^{\frac{t-10}{3}} + 80 = 60 (\frac{11}{30})^{t/3} +20$
Solve for t:
$60 (\frac{11}{30})^{t/3} +9(\frac{11}{30})^{\frac{-10}{3}}(\frac{11}{30})^{t/3} = 60 \\ \\ (\frac{11}{30})^{t/3} = \frac{60}{60+9(\frac{11}{30})^{\frac{-10}{3}}} \\ \\ \\ t = 3(\frac{ln(\frac{60}{60+9(\frac{11}{30})^{\frac{-10}{3}}})}{ln (\frac{11}{30})}) \\ \\ \\ t = 4.959$

This means the exact time it was brought indoors was about 2.5 seconds before 2:05 PM

8 0

3 years ago

7 squared minus y equals 6 then y equals

vova2212 [387]

Answer:

Y = 43

Step-by-step explanation:

7^2 - y = 6

49 - y = 6

subtract 49

-y = -43

divide by -1

y = 43

6 0

3 years ago

Can y’all help me please !

Leviafan [203]

no because she turned it only 90 degrees not 180.

180 would be a mirror reflection

6 0

3 years ago