Question

give the correct answer..?​

Answer 1

19. Solution:

Given ratio = 7:5

let the ratio constant be x

=> 7x:5x

Sum of any two adjacent angles of a parallelogram = 180°

7x+5x = 180°

12x = 180°

x = 180/12

x= 15

So, first angle = 7x => 7*15 = 105°

second angle = 5x => 5*15 = 75°

Step-by-step explanation:

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Answer 2

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18.Sum of observations/ number of observations =mean

1)total students=100

Number of boys =60

Number of girls=40

2) mean height of 100 students=150

Sum of heights of the 100

students=150000----(1)

3) mean. Height of 60 boys =170

Sum of heights of 60 boys =170x60=10200----(2)

Sum of the heights of 40 girls =(1) - (2)

=15000-10200

=4800

Mean height of 40 girls = 4800/40

=120

19.We know that the sum of two adjacent Angles in a parallelogram is 180°.

let the adjacent angles be 7x and 5x.

therefore 7x + 5x = 180°

= 12x = 180°

==> x = 180/12

==> x= 15°

hence, angle a = 7x

= 7 x 15

= 105°

angle b = 5x

= 5 x 15

= 75°

VERIFICATION:

sum of adjacent angles = 105 + 75

= 180° =

hence verified

thus the two adjacent angles are 105° and 75°.

other two angles are also 105° and 75° as we know opposite angles are same.