F.3 Maths (3)

1) Although someone has answered, I will answer it again.
7a + 5b = 3a + 8b
4a = 3b
4a/b = 3
a/b = 3/4
a:b = 3:4

2)Median = 67
There are 15 data, so the median is the 8th term. As the data are arranged in order already, just count from the first data (50) and get the 8th data, which is 67.

Range = 50 - 75
Range means to find the smallest and largest data.

3)Circumference of the base
= arc AB
=( 2 x 20 x Pi x 108/360 ) cm
= 12 Pi cm
= 37.7 cm (corr. to 3 sig. fig.)

4) Total number of visitors
= 20000 + 21000 + 21000 + 19000 + 20000
= 110000

The method is rounding-off method and correct the figures to 2 sig. fig.

1.
7a+5b=3a+8b

7a-3a=8b-5b

4a=3b

a/b=3/4

SO a:b=3:4