In a ΔPQR, S and T are mid–points of the sides PQ and PR respectively. U is a point on ST such that SU: UT = 2 : 5. If SU = 8, then the length of QR is–
60 men working 12hr a days complete a work in 30 days
1 Man work in 1 hr a day complete a work in = 30 × 60 × 12 = 21600 days
∴ 90 men working 8hr a day can complete the same work in = $21600\over90x8$ = 30 days
The ratio between boys and girls in a school is 6 : 8 respectively. If the number of boys is increased by 200 the ratio becomes 7 : 8 respectively. How many girls are there in the school?
The average of 6 quantities is 10. Therefore, the sum of all 6 quantities is 60. The average of 4 of them is 8. Therefore the sum of 4 quantities = 32 Therefore, the sum of the remaining two quantities = (60 – 32) = 28 Hence the sum average of the 2 qunatities
= $28\over2$= 14