81) a box consists of 100 shirts of which 88 are good, 8 have minor defects and 4 have major defects. ramesh, a shopkeeper will buy only those shirts which are good but ‘kewal’ another shopkeeper will not buy shirts with major defects. a shirt is taken out of the box at random. what is the probability that
i) ramesh will buy the selected shirt ?
ii)‘kewal’ will buy the selected shirt ?
76) the angles of depression of the top and bottom of a 50m high building from the top of a tower are 45° and 60° respectively. find the height of the tower and the horizontal distance between the tower and the building (use √3 = 1.73)
74) a well of diameter 4m is dug 21m deep. the earth taken out of it has been spread evenly all around it in the shape of a circular ring of width 3m to form an embankment. find the height of the embankment.
71) in fig. , are shown two arcs paq and pbq. arc paq is a part of circle with centre o and radius op while arc pbq is a semi-circle drawn on pq as diameter with centre m. if op = pq = 10 cm show that area of shaded region is 25 (√3 - "π" /6) cm2
70) in fig., abc is a triangle, coordinates of whose vertex a are (0, – 1). d and e respectively are the mid-points of the sides ab and ac and their coordinates are (1, 0) and (0, 1) respectively. if f is the mid-point of bc, find the areas of Δabc and Δdef.
In fig., is a decorative block, made up of two solids – a cube and a hemisphere. the base of the block is a cube of side 6 cm and the hemisphere fixed on the top has a diameter of 3.5 cm. find the total surface area of the block. (use π = 22/7)
explained by: brijesh sharma