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Natali5045456 [20]

1 year ago

12

40% of the students in a class are girls and the number of boys is 24 find the total number of students and the number of girls

1 answer:

navik [9.2K]1 year ago

7 0

Answer:

Girls = 16

Total students = 40

Step-by-step explanation:

40% of the students are girls, this means 60% of the students are boys.

To find the number of girls, setup a proportion using the percentages and actual number of students in the class. I am going to make the numerator the numbers that go with the girls and the denominator will be the numbers that go with the boys.

Also let's convert the percentages to decimals by moving the decimal two places left.

40% = 0.4 and 60% = 0.6

$\frac{.4}{.6} =\frac{g}{24} \\.6g=9.6\\\frac{.6g}{.6} =\frac{9.6}{.6} \\g=16$

Now let's find the total number of students by adding the number of girls to the number of boys.

16 + 24 = 40

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Sandra throws an object straight up into the air with initial velocity of 38 ft per square from platform that is 30 ft above the

expeople1 [14]

Answer:

3 seconds.

Step-by-step explanation:

We have been given that Sandra throws an object straight up into the air with initial velocity of 38 ft per second from platform that is 30 ft above the ground.

To find the time it will take for object to hit the ground, we will use formula:

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Upon substituting our given initial velocity and initial height, we will get:

$h(t)=-16t^2+38t+30$

We know that object will hit the ground, when height will be 0, so we will equate object's height equal to 0 and solve for t as:

$-16t^2+38t+30=0$

Divide by 2:

$-8t^2+19t+15=0$

Upon using quadratic formula, we will get:

$t=\frac{-b\pm\sqrt{b^2-4ac}}{2a}=\frac{-19\pm\sqrt{19^2-4(-8)(15)}}{2(-8)}$

$t=\frac{-19\pm\sqrt{361+480}}{-16}=\frac{-19\pm\sqrt{841}}{-16}$

$t=\frac{-19\pm29}{-16}$

$t=\frac{-19-29}{-16},t=\frac{-19+29}{-16}$

$t=\frac{-48}{-16},t=\frac{10}{-16}$

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7 0

3 years ago

The lengths of pregnancies are normally distributed with a mean of 269269 days and a standard deviation of 1515 days. a. Find th

kati45 [8]

Answer:

a. 0.38%

b. 266.75 days

Step-by-step explanation:

We have the following data, mean (m) 269 and standard deviation (sd) 15, therefore:

a. The first thing is to calculate the number z:

z (x) = (x - m) / sd

z (309) = (309-269) / 15 = 2.67

When looking in the normal distribution table (attached), we have that at this value of z, the probability is:

P (z> 2.67), that is to say we must look in the table -2.67 and this value corresponds to 0.0038, that is to say 0.38%

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invNorm (0.44) = -0.15

Find the corresponding number of days:

x = z * sd + m

we replace

d = -0.15 * 15 + 269 = 266.75 days

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Have a nice day!

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2 years ago

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