The first term of a g.p is 7 and the last term is 448 . the sum is 889 calculate the common ratio

Common ratio = 2

Explanation:

The formula for nth term of a geometric progression is given as:

aₙ = arⁿ⁻¹

Given the following values

First term a = 7

r = unknown

n = unknown

Last term = nth term = aₙ =  448

Sum of the terms = 889

Substituting

448 = 7rⁿ⁻¹

Divide both sides by 7

rⁿ⁻¹ = 448/7

rⁿ⁻¹ = 64

Converting 64 to a power

rⁿ⁻¹ = 2⁶

Equating the powers together,

n - 1 = 6

n = 6+1 = 7

Number of terms (n) = 7

Therefore, the common ratio of the geometric progression( r ) = 2

Explanation:

Given,

The density of Helium is

We need to find the density in Dg/μm

We know that,

1 g = 10 dg

1 cm³ = 10¹² μm³

So,

So, the density of Helium is equal to .