Question

8. (i) Ifa : b=5 : 7 and b: c = 14:15, find a : c.
(ii) If x:y= 2 : 7 and y:z= 9:11, find x:y:z.​

Answer 1

Answer:

i)A:B=5:7

B:C=14:15

A:B:C={A×B : B×B : B×C}

A:B:C=70:98:105

A:C=70:105

=14:21

=2:3

ii)X:Y=2:7

Y:Z=9:11

X:Y:Z=18:63:77{X×Y : Y×Y : Y×Z}

Answer 2

(i) Here is your answer:

Given : a/b = 5/7. (eq. i)

And ,b/c = 14/15. (eq. ii)

multiply eq. i and ii

a/ b × b/c = 5/7 × 14/15

a/c = 2/3

so, a:c = 2:3

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(ii) Given: x/ y = 2/7. (eq. i)

y/z = 9/11. (eq. ii)

In eq. (i)

x/y = 2/7

x/y = 2×9/7×9.

( multiply up and down by 9)

x/y = 18 / 63. ( eq. iii)

In eq. ( ii)

y/z = 9/11

y/z = 9×7/11×7

(multiply up and down by 7)

y/z = 63/77. ( eq. iv)

From eq. ( iii) and (iv), we conclude

x:y:z = 18:63:77

Hope this answer help you.