How to round 15,472,988 in ten thousands

Robin spent 25% more time on his research project than he had planned he’s been an extra h ours on the project which of the following expressions could represent the number of hours rob actually spent on the project

Given a normal distribution with µ =50 and σ =4, what is the probability that 5% of the values are less than what x values? between what two x values (symmetrically distributed around the mean) are 95 % of the values? instructions: show all your work as to how you have reached your answer. don’t simply state the results. show graphs where necessary.

How can you use equivalent fractions to know that 43/200 is between 1/5 and 1/4?