azaz1819
27.12.2019 •
Mathematics
Two circles, one with radius 10 inches and the other with radius 4 inches, are tangent at point q. two insects start crawling at the same time from point q: one along the larger circle at 3π inches per minute, the other along the smaller circle at 2.5π inches per minute. how much time has elapsed when the two insects meet again at point q?
(a) 15 minutes
(b) 30 minutes
(c) 40 minutes
(d) 1 hour
(e) 1 hour, 20 minutes
Solved
Show answers
More tips
- H Health and Medicine How Many Ribs Do Humans Have?...
- H Health and Medicine Simple and Effective: How to Get Rid of Cracked Heels...
- H Health and Medicine Relieving Swelling in Legs: Causes and Ways to Alleviate the Symptom...
- W Work and Career Мерчендайзинг – все, что нужно знать...
- O Other Everything You Need to Know About Kudyabliks...
- F Food and Cooking How to cook crayfish? Everything you need to know...
- F Food and Cooking Homemade kvass: recipe and brewing process...
- H Health and Medicine How to Choose the Right Tanning Cream?...
- S Style and Beauty Secrets of Tying a Pareo: 5 Ways...
- S Sport Running: How to Do It Right?...
Answers on questions: Mathematics
- M Mathematics Last week Tim had $42. He washed cars over the weekend and now has $61. How much money did he make washing cars?...
- M Mathematics Terri is growing at a rate of 6cm per year. If she is 132cm tall at 11 years old and she stops growing at the same rate at18 year old, how tall is she at her 18th birthday?...
- M Mathematics What is the inverse of the fraction f(x) = 2x + 1? h(x) = 1/2 x-1/2 h(x) = 1/2 x...
- G Geography Most of the pulling force that drives plate motion is produced...
- E English Who has a summary of the novel peak pages 1-135...
Ответ:
(E) 1hr 20 mins
Step-by-step explanation:
Radius of the larger circle = 10 inches
Radius of the smaller circle = 4 inches
Circumference of a circle = 2πr
For the larger circle, circumference = 2π(10)
=20π
For the smaller circle, circumference = 2π(4)
= 8π
Rate of larger circle = 3π inches /min
Rate of smaller circle = 2.5π inches/min
For the larger circle, it will take 20π/3π
= 20/3 mins to make one revolution
For the smaller circle, it will take 8π/2.5π
= 16/5 mins to make one revolution
To find the time taken for them to bisect, find the LCM of both times. Get the denominators of both numbers equal to the other.
20/ 3 = 100/15
16/5 = 48/15
The LCM of 48 and 100 = 1200
48 = 2*2*2*2*3
100 = 2*2*5*5
LCM = 2*2*2*2*3*5*5
= 1200
So we have 1200/15 = 80 mins
= 60 mins + 20mins
= 1 hr 20 mins
Ответ: