16. (a) Find the Highest Common Factor (HCF) of 30 and 42.

6

Step-by-step explanation: By checking the factors of both numbers, you see that 6 is their greatest common factor.

30: 1, 2, 3, 5, 6, 10, 15, 30

42: 1, 2, 3, 6, 7, 14, 21, 42

Hope this helps!

4.2 mi²

Step-by-step explanation:

Volume of a cone = (1/3)πr²h, where r = radius and h = height

(1/3)πr²h

= (1/3)×π×1²×4

= 4π/3

= 4.2 mi² (rounded to the nearest tenth)