There are 20 balls in a bag. The probability is 0.25 of picking a red ball. If one more red ball is added, what is the new probability of picking a red ball at random?

Convert 0.25 into a fraction where 20 is the denominator as there are 20 balls in total in the bag. 0.25 is the same as 1/4 and to convert this to 20 as the denominator multiply both the top and the bottom by 5 so the new fraction is 5/20. As the new ball to be added is red it is within both the numerator and denominator so add one to both to get the new probability of 6/21. Simplify this if possible (although this example 6/21 is the simplest form). As the question has given the original probability in a decimal, convert the fraction to a decimal to get 0.2857.

AL
Answered by Alex L. Maths tutor

10412 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve the simultaneous equations. 2x + y = 18, x − y = 6


Solve 8x + 9y = 3 and x + y = 0.


Solve x^2 = 4(x – 3)^2


Fred is reshaping his garden. He decides to make into a right-angled triangle ABC. The length AB= 5m and the length BC= 12 What is the length of AC?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences