The prices of four food items in a shopping basket are €5, €7, €11 and €2.
Find the weighted mean price of these items using the weights 3, 2, 1 and 4
respectively.
Find the standard deviation of the numbers 9, 3, 10 and 2 correct to one decimal place.
Use the answer from question two to find the standard deviation of the numbers 19, 13, 20 and 12, correct to one decimal place.
Use the answer from question two to find the standard deviation of the numbers 90, 30, 100 and 20 correct to the nearest whole number.
In a certain subject, the examination consists of a project, a practical test, and a written paper.
The overall result is the weighted mean of the percentages achieved in these three components,
using the weights 4, 2 and 5, respectively.
Norman scores 40% in the project and 60% in the practical.
What percentage mark must he get in the written paper in order to get an overall
result of 55%?
Find the standard deviation of the sequence
a, a+d, a+2d, a+3d, a+4d, a+5d, a+6d.
The mean of the real numbers a and b is µ.
The standard deviation is σ.
Find µ2 - σ2.
k - 2 and 3k - 4 are postive integers.
Their standard deviation is 3.
Find the value of k.