This is a way to work it out
(126) times (1/2 to the x/11 power) = 15% times 126
(1/2) to the x/11 power = 0.15
Take the log of both sides :
(x/11) times log(1/2) = log(0.15)
Multiply both sides by 11 :
'x' times log(1/2) = 11 x log(0.15)
Divide both sides by " log(1/2) " :
x = 11 x log(0.15)/log(1/2) = <em><u>30.107 years</u></em> (rounded)
That's the time it takes for <em><u>any-size</u></em> sample of this substance
to decay to 15% of its original size.
The Bernoulli distribution is a distribution whose random variable can only take 0 or 1
- The value of E(x2) is p
- The value of V(x) is p(1 - p)
- The value of E(x79) is p
<h3>How to compute E(x2)</h3>
The distribution is given as:
p(0) = 1 - p
p(1) = p
The expected value of x2, E(x2) is calculated as:

So, we have:

Evaluate the exponents

Multiply

Add

Hence, the value of E(x2) is p
<h3>How to compute V(x)</h3>
This is calculated as:

Start by calculating E(x) using:

So, we have:


Recall that:

So, we have:

Factor out p

Hence, the value of V(x) is p(1 - p)
<h3>How to compute E(x79)</h3>
The expected value of x79, E(x79) is calculated as:

So, we have:

Evaluate the exponents

Multiply

Add

Hence, the value of E(x79) is p
Read more about probability distribution at:
brainly.com/question/15246027
Answer:
she spent 75%
Step-by-step explanation: