When the numbers from 1 to 100 are written, in how many different numbers does the digit 3 appear?

The time it takes a student to walk from the dorm to the chemistry lab follows roughly a Normaldistribution with a mean of 20 mi

creativ13 [48]

Answer:

95.15%

Step-by-step explanation:

We have that the mean (m) is equal to 20, the standard deviation (sd) 3

They ask us for P (x <25)

For this, the first thing is to calculate z, which is given by the following equation:

z = (x - m) / sd

We have all these values, replacing we have:

z = (25 - 20) / (3)

z = 1.66

With the normal distribution table (attached), we have that at that value, the probability is:

P (z <1.66) = 0.9515

Which means that the probability that it arrives before 25 minutes is 95.15%

6 0

3 years ago

I have an easy and quick question. So the picture shows an answered question but how do you know to divide? I just don't underst

11111nata11111 [884]

Answer:

Ok so u know to divide bc u r trying to isolate the variable and that means undoing the function in this case 0.6 is multiplied to p so u do the opposite which is division

tada

Hope this helps :)

Pls give brainliest XD :)

8 0

3 years ago

Read 2 more answers

The article "Occurrence and Distribution of Ammonium in Iowa Groundwater" (K. Schilling, Water Environment Research, 2002:177–18

Papessa [141]

Answer: 95% confidence interval for the difference between the proportions would be (1.31, 1.39).

Step-by-step explanation:

Since we have given that

Number of alluvial wells = 349

Number of quaternary wells = 143

Number of alluvial wells that had concentrations above 0.1 = 182

Number of quaternary wells that had concentrations above 0.1 = 112

Average of alluvial wells = 0.27

Standard deviation = 0.4

Average of quaternary wells = 1.62

Standard deviation =1.70

So, 95% confidence interval gives

alpha = 5% level of significance.

$\dfrac{\alpha}{2}=2.5\%\\\\z_{\frac{\alpha}{2}}=1.96$

So, 95% confidence interval becomes,

$(1.62-0.27)\pm 1.96\sqrt{\dfrac{0.4^2}{349}+\dfrac{1.7^2}{143}}\\\\=1.35\pm 1.96\times 0.020\\\\=(1.35-0.040,1.35+0.040)\\\\=(1.31,1.39)$

Hence, 95% confidence interval for the difference between the proportions would be (1.31, 1.39).

6 0

3 years ago

A can in the shape of a cylinder has a diameter of 10 cm and a height of 6 cm. how much wrapping paper is needed to cover the cy

Sergeeva-Olga [200]

Answer:

Step-by-step explanation:

To determine the amount of wrapping paper needed to cover the can, we would determine the total surface area of the cylindrical can. The formula for determining the total surface area of a cylinder is expressed as

Total surface area = 2πr² + 2πrh

Where

r represents the radius of the cylinder.

h represents the height of the cylinder.

π is a constant whose value is 3.14

From the information given,

Diameter = 10 cm

Radius = diameter/2 = 10/2

Radius = 5 cm

Height = 6 cm

Therefore,

Total surface area = (2 × 3.14 × 5²) + (2 × 3.14 × 5 × 6)

= 157 + 188.4 = 345.4 cm²

345 cm² of wrapping paper is needed to cover the cylinder.

2) Volume of cylinder = πr²h

Volume of cone = 1/3πr²h

3 × Volume of cone = πr²h

The volume of the cylinder is 3 times greater than the volume of the cone. Therefore, the volume of the cone is 1/3 times lesser than the volume if the cylinder.

5 0

3 years ago

The density of a certain material is such that it weighs 71 pounds for every 2.5 gallons of volume. Express this density in tons

kvasek [131]

Answer:

$d=3.75\ \text{tons per cubic meter}$

Step-by-step explanation:

Given that,

Mass of a certain material, m = 71 pounds

Since, 1 ton = 2000 pounds

71 pounds = 0.0355 ton

Volume of the material, V = 2.5 gallons

Since, 1 m³ = 264.172 gallon

2.5 gallon = (2.5/264.172 ) m³

Density,

$d=\dfrac{m}{V}\\\\d=\dfrac{0.0355\ \text{tons}}{\dfrac{2.5}{264.172}\ m^3}\\\\d=3.75\ \text{tons per cubic meter}$

5 0

3 years ago

When the numbers from 1 to 100 are written, in how many different numbers does the digit 3 appear?​

When the numbers from 1 to 100 are written, in how many different numbers does the digit 3 appear?