Answer please I will give brainiest to the one who answers first.

$1,094,748.09$8600.2811 years, 10 months

Step-by-step explanation:

a) The compound interest formula can be used:

  A = P(1 +r/n)^(nt)

where P is the principal invested at annual rate r compounded n times per year for t years.

  A = $750,000(1 +.038/4)^(4·10) ≈ $1,094,748.09

Tamsyn's account will have a balance of $1,094,748.09 when she retires.

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b1) The amortization formula is good for this.

  A = P(r/n)/(1 -(1 +r/n)^(-nt))

where P is the amount earning interest at annual rate r compounded n times per year for t years.

  A = $1,094,748.09(0.049/12)/(1 - (1 +0.049/12)^(-12·15)) ≈ $8600.28

Tamsyn can withdraw $8600.28 per month for 15 years.

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b2) The account balance after n months will be ...

  B = P(1 +r/12)^n -A((1+r/12)^n -1)/(r/12)

Filling in the known values and solving for n, we have ...

  300,000 = 1,094,748.09(1.1.00408333^n) -8600.28(1.00408333^n -1)/.000408333

  300,000 = 1,094,748.09(1.1.00408333^n) -2,106,191.02(1.00408333^n -1)

  -1,806,191.02 = -1,011,442.93(1.00408333^n)

  1.785757 = 1.00408333^n

  n = log(1.785757)/log(1.00408333) = 142.3

After about 11 years 10 months, the account balance will be $300,000.

So, at the beginning there are a total of 25*3=75 siblings (we can assume that each of them had exactly 3 siblings, that's what average means; that we can assume this).

Now we have 25+1=26 students and the number of siblings is 75+8=83

and the average is, and rounded it's 3.19.