SOLUTION: two concentric circles have radii 12cm and 28cm respectively. if the larger circle has an area of 98cm square. calculate the area ratio of the larger circle to the smaller circle a

Question 1200000: two concentric circles have radii 12cm and 28cm respectively. if the larger circle has an area of 98cm square. calculate the area ratio of the larger circle to the smaller circle and hence calculate the area of the smaller circle
Found 3 solutions by greenestamps, ikleyn, Alan3354:
Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!

The given information is inconsistent; if the radius of the larger circle is 28cm, then its area is not 98 cm^2.

Very probably, the intent of the problem is to teach the concept that the ratio of area measurements in two similar figures is the square of the ratio of linear measurements.

The ratio of linear measurements in the two circles is 12:28 = 3:7, so the ratio of area measurements is 3^2:7^2 = 9:49.

Then, if we use the (incorrect) value of 98 cm^2 for the area of the larger circle, then the area of the smaller circle will be 98*(9/49) = 18 cm^2.

ANSWER (using incorrect given information): 18 cm^2

Answer by ikleyn(52803)   (Show Source): You can put this solution on YOUR website!
.

Whichever intent of this incorrect problem would be,
the problem is incorrect and is only good to throw it to the closest garbage bin.

The author deserves to get a ticket for his total mathematical illiteracy
and a serious warning for posting nonsense to this forum.

//////////////////

        To the managers of this project

I noticed today that some visitor posts non-sensical problems to the forum.

I ask you to remove this person from his position at the project
in order for he does not liter the Internet and does not fool the heads of tutors.

Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
two concentric circles have radii 12cm and 28cm respectively.
--------------
"respectively" is superfluous, not needed, contributes nothing.
RELATED QUESTIONS
Two concentric circles have radii of 16 cm and 34 cm. Find the length of the chord of... (answered by josgarithmetic)
3 concentric circles have radii of 5 cm, 10 cm and 15 cm. the chords of the two larger... (answered by greenestamps)
Find the area of the region between two concentric circles with radii 9 and 6. (answered by funmath)
(Bonus) Concentric circles have the same center but different radii. Write equations for... (answered by Fombitz)
The radii of two circles are 10cm and 11cm.By how many square centimeters is the area of... (answered by Cromlix)
find the area of the space enclosed by two concentric circles of radii 15cm &... (answered by edjones)
[ Find the area enclosed between two concentric circles of radii 6.3 cm and 8.4 cm. A... (answered by TimothyLamb)
Two concentric circles are drawn so that the shaded area is equal to the unshaded area.... (answered by josgarithmetic)
Two concentric circles have diameters of 672 and 840. Find the length of a chord of the... (answered by robertb)