Alfie has a £10 note He buys 3 pens costing £1.45 each and
some pencils costing 90p each.
If Alfie gets £2.05 change, how many
pencils does he buy?
What is the answer?

4 pencils

Step-by-step explanation:

3*1.45 = 4.35 ---> spent for the pens

( 10 -[ 4.35 + 2.05] ) = money spent on pencils

0.9x= 3.6

x=3.6/0.9 = 4

The probability is 0.97682

Step-by-step explanation:

We start by finding the z-values of the runner times given.

Mathematically;

z-score = (x-mean)/SD

From the question, mean = 13 seconds and SD = 0.3 seconds

So for 12.4 seconds, we have;

z = (12.4-13)/0.3 = -0.6/0.3 = -2

For 14 seconds, we have;

z = (14-13)/0.3= 1/0.3 = 3.33

So the probability we want to calculate is;

P(-2<z<3.33)

We can find this using the standard normal distribution table

Mathematically;

P(-2<z<3.33) = P(z<3.33) - P(z < -2)

Using the standard normal distribution table, the value of this is;

P(-2<z<3.33) = 0.97682