Marie wants to make a cone-shaped witch's hat for a masquerade ball. How much material will it need if it counts on an annular rim with diameters of 28cm and 44cm? Hat side length is 30cm. Add 5% of the material to the bust. Round to cm2.

Correct result:

S =  2335 cm2

#### Solution:

$D_{1}=28 \ \text{cm} \ \\ D_{2}=44 \ \text{cm} \ \\ \ \\ s=30 \ \text{cm} \ \\ q=1 + \dfrac{ 5 }{ 100 }=\dfrac{ 21 }{ 20 }=1.05 \ \\ \ \\ r_{1}=D_{1}/2=28/2=14 \ \text{cm} \ \\ r_{2}=D_{2}/2=44/2=22 \ \text{cm} \ \\ \ \\ S_{1}=\pi \cdot \ r_{2}^2 - \pi \cdot \ r_{1}^2=3.1416 \cdot \ 22^2 - 3.1416 \cdot \ 14^2 \doteq 904.7787 \ \text{cm}^2 \ \\ \ \\ S_{2}=\pi \cdot \ r_{1} \cdot \ s=3.1416 \cdot \ 14 \cdot \ 30 \doteq 1319.4689 \ \text{cm}^2 \ \\ \ \\ S=q \cdot \ (S_{1}+S_{2})=1.05 \cdot \ (904.7787+1319.4689)=2335 \ \text{cm}^2$

Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!

Please write to us with your comment on the math problem or ask something. Thank you for helping each other - students, teachers, parents, and problem authors.

Tips to related online calculators
Do you want to convert length units?
Do you want to round the number?

#### You need to know the following knowledge to solve this word math problem:

We encourage you to watch this tutorial video on this math problem:

## Next similar math problems:

• Ace
The length of segment AB is 24 cm and the point M and N divided it into thirds. Calculate the circumference and area of this shape.
• Circular lawn
Around a circular lawn area is 2 m wide sidewalk. The outer edge of the sidewalk is curb whose width is 2 m. Curbstone and the inner side of the sidewalk together form a concentric circles. Calculate the area of the circular lawn and the result round to 1
• Roller
Roller has a diameter of 0.96 m and a width 169 cm. How many m2 of road level when he turns 42-times?
• Cutting circles
From the square 1 m side we have to cut the circles with a radius of 10 cm. How many discs we cut and how many percent will be waste?
• Content area and percents
Determine what percentage is smaller cube surface, when the surface area of the wall decreases by 25%.
• The Chemistry test
The Chemistry test contained 8 questions, each with 3 points. Peter scored 21 points. How many percent did Peter write a test?
• Percents
How many percents is 900 greater than the number 750?
Calculate how many percent will increase the length of an HTML document, if any ASCII character unnecessarily encoded as hexadecimal HTML entity composed of six characters (ampersand, grid #, x, two hex digits and the semicolon). Ie. space as: &#x20;
• Persons
Persons surveyed:100 with result: Volleyball=15% Baseball=9% Sepak Takraw=8% Pingpong=8% Basketball=60% Find the average how many like Basketball and Volleyball. Please show your solution.
• Percentages
52 is what percent of 93?
• Walking
Of the 450 students at the school, 432 walks to school. What percentage is this?
• Summerjob
The temporary workers planted new trees. Of the total number of 500 seedlings, they managed to plant 426. How many percents did they meet the daily planting limit?
• Reward
Janko and Peter divided the reward from the brigade so that Peter got 5/8 of the reward. What percentage of Janko's reward got?
• Profit gain
If 5% more is gained by selling an article for Rs. 350 than by selling it for Rs. 340, the cost of the article is:
• Highway repair
The highway repair was planned for 15 days. However, it was reduced by 30%. How many days did the repair of the highway last?
• Art school
Every fifth pupil 9A goes to art school. How many percent of pupils in class 9A go to art school?
• Dining questionnaire
In the class of 32 pupils, the class teacher delivered a satisfaction questionnaire to the school canteen. Eleven people have questioned whether they are satisfied with the dining room. The completed questionnaire also included the vote of the class teach