78 is the geometric mean of 30 and what number

202.8

Step-by-step explanation:

The geometric mean of 2 numbers a and b is

Here a = 30 and mean = 78, thus

= 78

To clear the radical square both sides

( )² = 78², that is

30b = 6084 ( divide both sides by 30 )

b = = 202.8

d) 30 units^2

area of rectangle = l × b

we know,

length = 10 unit

breadth = 3 unit

applying the formula,

= l × b

= 10 × 3

= 30 unit^2

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168

step-by-step explanation:

i am pretty sure that the answer is 168