Answer:
d) 303 8/9
Step-by-step explanation:
4th term = ar^3 and 5th = ar^4 where a = first term and r = common ratio.
So ar^4 / ar^3
= r = 45/-15 = -3.
Working back,:
The first term a = ar^3/ r^3
= -15 / (-3)^3
= -15/-27
= 5/9
Sum of n terms = a * (r^n - 1)/(r-1)
= 5/9 * ((-3)^7 - 1 ) / (-3 -1)
= 303 8/9
429.8x 4 days=1,719.2miles driven on a four day trip.
1.326 grams of NH3 are required to produce 4.65 g of HF.
Step-by-step explanation:
Balanced chemical reaction is written first to know the number of moles taking part in original reaction.
NH3 +3 F2 ⇒3 HF + NF3
Given:
mass of HF = 4.65
First the number of moles of HF in 4.65 grams is calculated by using the formula:
number of moles (n) = 
atomic mass of HF = 20 grams/mole
putting the values in the above equation number of moles can be found.
n = 
= 0.235 moles of HF are given.
From the equation it can be said that:
1 mole of NH3 reacts to form 3 moles of HF
so, x moles of NH3 would react to form 0.235 moles of HF
= 
3x = 0.235
x = 
x = 0.078 moles of NH3 is required.
The moles are converted to mass by applying the formula:
mass = atomic mass X number of moles (atomic mass of NH3 = 17 grams/mole)
putting the values in the formula
mass = 17 X 0.078
mass = 1.326 grams
Answer:
3/20
Step-by-step explanation:
Given that :
Share for 5 persons = 3/4 of a whole pizza
Each person gets an equal size of the share :
Hence, share per person :
Portion of pizza / number of persons
3/4 ÷ 5
3/4 * 1/5
= (3*1) / (4*5)
= 3/20
Find an easy to read point such as (10, 40).
The ratio of y to x is 40/10 = 4/1.
Now look in your choices and find a point in which y is 4 times x.
The only such point is (5, 20).
Answer: C. (5, 20)