The time taken by Anu, Tanu, and Manu is in the ratio \( 5 : 8 : 10 \).
Let their respective times be \(5x, 8x, 10x\). The total work is \(W = 40x\) units.
Their individual rates are:
\[ \text{Anu's rate} = \frac{W}{5x} = 8, \quad \text{Tanu's rate} = \frac{W}{8x} = 5, \quad \text{Manu's rate} = \frac{W}{10x} = 4. \]
Their combined rate is \(8 + 5 + 4 = 17\) units/hr. They complete the job in 32 hours, so:
\[ 40x = 17 \times 32 \implies x = 13.6. \]
Anu and Tanu work for 6 days, for 6 hours and 40 minutes each day. This is \(6 \times \frac{20}{3}\) hours per day.
\[ \text{Total hours worked by Anu and Tanu} = 6 \times \frac{20}{3} = 40 \text{ hours}. \]
The work done by Anu and Tanu together is:
\[ (8 + 5) \times 40 = 13 \times 40 = 520 \text{ units}. \]
The remaining work is:
\[ 40x - 520 = 544 - 520 = 24 \text{ units}. \]
Let \(y\) be the time Manu takes to complete the remaining work at his rate of 4 units/hr:
\[ 4y = 24 \implies y = 6 \text{ hours}. \]
Manu will take 6 hours to complete the remaining job.
A box contains 16 red, 12 white, and 15 yellow identical marbles. A man picks one marble at a time without replacement. How many times must he pick a marble to be 100% certain of picking at least 3 white marbles?